| Message ID | 20190603170306.49099-3-nitesh@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: Support for page hinting | expand |
On Mon, Jun 3, 2019 at 10:04 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: > > Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the > host. If it is available and page_hinting_flag is set to true, page_hinting > is enabled and its callbacks are configured along with the max_pages count > which indicates the maximum number of pages that can be isolated and hinted > at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are > reported. To prevent any false OOM max_pages count is set to 16. > > By default page_hinting feature is enabled and gets loaded as soon > as the virtio-balloon driver is loaded. However, it could be disabled > by writing the page_hinting_flag which is a virtio-balloon parameter. > > Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> > --- > drivers/virtio/virtio_balloon.c | 112 +++++++++++++++++++++++++++- > include/uapi/linux/virtio_balloon.h | 14 ++++ > 2 files changed, 125 insertions(+), 1 deletion(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index f19061b585a4..40f09ea31643 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -31,6 +31,7 @@ > #include <linux/mm.h> > #include <linux/mount.h> > #include <linux/magic.h> > +#include <linux/page_hinting.h> > > /* > * Balloon device works in 4K page units. So each page is pointed to by > @@ -48,6 +49,7 @@ > /* The size of a free page block in bytes */ > #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ > (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) > +#define VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES 16 > > #ifdef CONFIG_BALLOON_COMPACTION > static struct vfsmount *balloon_mnt; > @@ -58,6 +60,7 @@ enum virtio_balloon_vq { > VIRTIO_BALLOON_VQ_DEFLATE, > VIRTIO_BALLOON_VQ_STATS, > VIRTIO_BALLOON_VQ_FREE_PAGE, > + VIRTIO_BALLOON_VQ_HINTING, > VIRTIO_BALLOON_VQ_MAX > }; > > @@ -67,7 +70,8 @@ enum virtio_balloon_config_read { > > struct virtio_balloon { > struct virtio_device *vdev; > - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; > + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, > + *hinting_vq; > > /* Balloon's own wq for cpu-intensive work items */ > struct workqueue_struct *balloon_wq; > @@ -125,6 +129,9 @@ struct virtio_balloon { > > /* To register a shrinker to shrink memory upon memory pressure */ > struct shrinker shrinker; > + > + /* object pointing at the array of isolated pages ready for hinting */ > + struct hinting_data *hinting_arr; Just make this an array of size VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES. It will save a bunch of complexity later. > }; > > static struct virtio_device_id id_table[] = { > @@ -132,6 +139,85 @@ static struct virtio_device_id id_table[] = { > { 0 }, > }; > > +#ifdef CONFIG_PAGE_HINTING Instead of having CONFIG_PAGE_HINTING enable this, maybe we should have virtio-balloon enable CONFIG_PAGE_HINTING. > +struct virtio_balloon *hvb; > +bool page_hinting_flag = true; > +module_param(page_hinting_flag, bool, 0444); > +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); > + > +static bool virtqueue_kick_sync(struct virtqueue *vq) > +{ > + u32 len; > + > + if (likely(virtqueue_kick(vq))) { > + while (!virtqueue_get_buf(vq, &len) && > + !virtqueue_is_broken(vq)) > + cpu_relax(); > + return true; Is this a synchronous setup? It seems kind of wasteful to have a thread busy waiting here like this. It might make more sense to just make this work like the other balloon queues and have a wait event with a wake up in the interrupt handler for the queue. > + } > + return false; > +} > + > +static void page_hinting_report(int entries) > +{ > + struct scatterlist sg; > + struct virtqueue *vq = hvb->hinting_vq; > + int err = 0; > + struct hinting_data *hint_req; > + u64 gpaddr; > + > + hint_req = kmalloc(sizeof(*hint_req), GFP_KERNEL); > + if (!hint_req) > + return; Why do we need another allocation here? Couldn't you just allocate hint_req on the stack and then use that? I think we might be doing too much here. All this really needs to look like is something along the lines of tell_host() minus the wait_event. > + gpaddr = virt_to_phys(hvb->hinting_arr); > + hint_req->phys_addr = cpu_to_virtio64(hvb->vdev, gpaddr); > + hint_req->size = cpu_to_virtio32(hvb->vdev, entries); > + sg_init_one(&sg, hint_req, sizeof(*hint_req)); > + err = virtqueue_add_outbuf(vq, &sg, 1, hint_req, GFP_KERNEL); > + if (!err) > + virtqueue_kick_sync(hvb->hinting_vq); > + > + kfree(hint_req); > +} > + > +int page_hinting_prepare(void) > +{ > + hvb->hinting_arr = kmalloc_array(VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, > + sizeof(*hvb->hinting_arr), GFP_KERNEL); > + if (!hvb->hinting_arr) > + return -ENOMEM; > + return 0; > +} > + Why make the hinting_arr a dynamic allocation? You should probably just make it a static array within the virtio_balloon structure. Then you don't have the risk of an allocation failing and messing up the hints. > +void hint_pages(struct list_head *pages) > +{ > + struct page *page, *next; > + unsigned long pfn; > + int idx = 0, order; > + > + list_for_each_entry_safe(page, next, pages, lru) { > + pfn = page_to_pfn(page); > + order = page_private(page); > + hvb->hinting_arr[idx].phys_addr = pfn << PAGE_SHIFT; > + hvb->hinting_arr[idx].size = (1 << order) * PAGE_SIZE; > + idx++; > + } > + page_hinting_report(idx); > +} > + Getting back to my suggestion from earlier today. It might make sense to not bother with the PAGE_SHIFT or PAGE_SIZE multiplication if you just record everything in VIRTIO_BALLOON_PAGES intead of using the actual address and size. > +void page_hinting_cleanup(void) > +{ > + kfree(hvb->hinting_arr); > +} > + Same comment here. Make this array a part of virtio_balloon and you don't have to free it. > +static const struct page_hinting_cb hcb = { > + .prepare = page_hinting_prepare, > + .hint_pages = hint_pages, > + .cleanup = page_hinting_cleanup, > + .max_pages = VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, > +}; With the above changes prepare and cleanup can be dropped. > +#endif > + > static u32 page_to_balloon_pfn(struct page *page) > { > unsigned long pfn = page_to_pfn(page); > @@ -488,6 +574,7 @@ static int init_vqs(struct virtio_balloon *vb) > names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate"; > names[VIRTIO_BALLOON_VQ_STATS] = NULL; > names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; > + names[VIRTIO_BALLOON_VQ_HINTING] = NULL; > > if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { > names[VIRTIO_BALLOON_VQ_STATS] = "stats"; > @@ -499,11 +586,18 @@ static int init_vqs(struct virtio_balloon *vb) > callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; > } > > + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { > + names[VIRTIO_BALLOON_VQ_HINTING] = "hinting_vq"; > + callbacks[VIRTIO_BALLOON_VQ_HINTING] = NULL; > + } > err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, > vqs, callbacks, names, NULL, NULL); > if (err) > return err; > > + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) > + vb->hinting_vq = vqs[VIRTIO_BALLOON_VQ_HINTING]; > + > vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE]; > vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE]; > if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { > @@ -942,6 +1036,14 @@ static int virtballoon_probe(struct virtio_device *vdev) > if (err) > goto out_del_balloon_wq; > } > + > +#ifdef CONFIG_PAGE_HINTING > + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) && > + page_hinting_flag) { > + hvb = vb; > + page_hinting_enable(&hcb); > + } > +#endif > virtio_device_ready(vdev); > > if (towards_target(vb)) > @@ -989,6 +1091,12 @@ static void virtballoon_remove(struct virtio_device *vdev) > destroy_workqueue(vb->balloon_wq); > } > > +#ifdef CONFIG_PAGE_HINTING > + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { > + hvb = NULL; > + page_hinting_disable(); > + } > +#endif > remove_common(vb); > #ifdef CONFIG_BALLOON_COMPACTION > if (vb->vb_dev_info.inode) > @@ -1043,8 +1151,10 @@ static unsigned int features[] = { > VIRTIO_BALLOON_F_MUST_TELL_HOST, > VIRTIO_BALLOON_F_STATS_VQ, > VIRTIO_BALLOON_F_DEFLATE_ON_OOM, > + VIRTIO_BALLOON_F_HINTING, > VIRTIO_BALLOON_F_FREE_PAGE_HINT, > VIRTIO_BALLOON_F_PAGE_POISON, > + VIRTIO_BALLOON_F_HINTING, > }; > > static struct virtio_driver virtio_balloon_driver = { > diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h > index a1966cd7b677..25e4f817c660 100644 > --- a/include/uapi/linux/virtio_balloon.h > +++ b/include/uapi/linux/virtio_balloon.h > @@ -29,6 +29,7 @@ > #include <linux/virtio_types.h> > #include <linux/virtio_ids.h> > #include <linux/virtio_config.h> > +#include <linux/page_hinting.h> > > /* The feature bitmap for virtio balloon */ > #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */ > @@ -36,6 +37,7 @@ > #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */ > #define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */ > #define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */ > +#define VIRTIO_BALLOON_F_HINTING 5 /* Page hinting virtqueue */ > > /* Size of a PFN in the balloon interface. */ > #define VIRTIO_BALLOON_PFN_SHIFT 12 > @@ -108,4 +110,16 @@ struct virtio_balloon_stat { > __virtio64 val; > } __attribute__((packed)); > > +#ifdef CONFIG_PAGE_HINTING > +/* > + * struct hinting_data- holds the information associated with hinting. > + * @phys_add: physical address associated with a page or the array holding > + * the array of isolated pages. > + * @size: total size associated with the phys_addr. > + */ > +struct hinting_data { > + __virtio64 phys_addr; > + __virtio32 size; > +}; So in order to avoid errors this should either have "__attribute__((packed))" added or it should be changed to a pair of u32 or u64 values so that it will always be the same size regardless of what platform it is built on. > +#endif > #endif /* _LINUX_VIRTIO_BALLOON_H */ > -- > 2.21.0 >
On 04.06.19 00:38, Alexander Duyck wrote: > On Mon, Jun 3, 2019 at 10:04 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: >> >> Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the >> host. If it is available and page_hinting_flag is set to true, page_hinting >> is enabled and its callbacks are configured along with the max_pages count >> which indicates the maximum number of pages that can be isolated and hinted >> at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are >> reported. To prevent any false OOM max_pages count is set to 16. >> >> By default page_hinting feature is enabled and gets loaded as soon >> as the virtio-balloon driver is loaded. However, it could be disabled >> by writing the page_hinting_flag which is a virtio-balloon parameter. >> >> Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> >> --- >> drivers/virtio/virtio_balloon.c | 112 +++++++++++++++++++++++++++- >> include/uapi/linux/virtio_balloon.h | 14 ++++ >> 2 files changed, 125 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c >> index f19061b585a4..40f09ea31643 100644 >> --- a/drivers/virtio/virtio_balloon.c >> +++ b/drivers/virtio/virtio_balloon.c >> @@ -31,6 +31,7 @@ >> #include <linux/mm.h> >> #include <linux/mount.h> >> #include <linux/magic.h> >> +#include <linux/page_hinting.h> >> >> /* >> * Balloon device works in 4K page units. So each page is pointed to by >> @@ -48,6 +49,7 @@ >> /* The size of a free page block in bytes */ >> #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ >> (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) >> +#define VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES 16 >> >> #ifdef CONFIG_BALLOON_COMPACTION >> static struct vfsmount *balloon_mnt; >> @@ -58,6 +60,7 @@ enum virtio_balloon_vq { >> VIRTIO_BALLOON_VQ_DEFLATE, >> VIRTIO_BALLOON_VQ_STATS, >> VIRTIO_BALLOON_VQ_FREE_PAGE, >> + VIRTIO_BALLOON_VQ_HINTING, >> VIRTIO_BALLOON_VQ_MAX >> }; >> >> @@ -67,7 +70,8 @@ enum virtio_balloon_config_read { >> >> struct virtio_balloon { >> struct virtio_device *vdev; >> - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; >> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, >> + *hinting_vq; >> >> /* Balloon's own wq for cpu-intensive work items */ >> struct workqueue_struct *balloon_wq; >> @@ -125,6 +129,9 @@ struct virtio_balloon { >> >> /* To register a shrinker to shrink memory upon memory pressure */ >> struct shrinker shrinker; >> + >> + /* object pointing at the array of isolated pages ready for hinting */ >> + struct hinting_data *hinting_arr; > > Just make this an array of size VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES. > It will save a bunch of complexity later. +1 [...] > >> +struct virtio_balloon *hvb; >> +bool page_hinting_flag = true; >> +module_param(page_hinting_flag, bool, 0444); >> +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); >> + >> +static bool virtqueue_kick_sync(struct virtqueue *vq) >> +{ >> + u32 len; >> + >> + if (likely(virtqueue_kick(vq))) { >> + while (!virtqueue_get_buf(vq, &len) && >> + !virtqueue_is_broken(vq)) >> + cpu_relax(); >> + return true; > > Is this a synchronous setup? It seems kind of wasteful to have a > thread busy waiting here like this. It might make more sense to just > make this work like the other balloon queues and have a wait event > with a wake up in the interrupt handler for the queue. +1 [...] > >> + gpaddr = virt_to_phys(hvb->hinting_arr); >> + hint_req->phys_addr = cpu_to_virtio64(hvb->vdev, gpaddr); >> + hint_req->size = cpu_to_virtio32(hvb->vdev, entries); >> + sg_init_one(&sg, hint_req, sizeof(*hint_req)); >> + err = virtqueue_add_outbuf(vq, &sg, 1, hint_req, GFP_KERNEL); >> + if (!err) >> + virtqueue_kick_sync(hvb->hinting_vq); >> + >> + kfree(hint_req); >> +} >> + >> +int page_hinting_prepare(void) >> +{ >> + hvb->hinting_arr = kmalloc_array(VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, >> + sizeof(*hvb->hinting_arr), GFP_KERNEL); >> + if (!hvb->hinting_arr) >> + return -ENOMEM; >> + return 0; >> +} >> + > > Why make the hinting_arr a dynamic allocation? You should probably > just make it a static array within the virtio_balloon structure. Then > you don't have the risk of an allocation failing and messing up the > hints. +1 > >> +void hint_pages(struct list_head *pages) >> +{ >> + struct page *page, *next; >> + unsigned long pfn; >> + int idx = 0, order; >> + >> + list_for_each_entry_safe(page, next, pages, lru) { >> + pfn = page_to_pfn(page); >> + order = page_private(page); >> + hvb->hinting_arr[idx].phys_addr = pfn << PAGE_SHIFT; >> + hvb->hinting_arr[idx].size = (1 << order) * PAGE_SIZE; >> + idx++; >> + } >> + page_hinting_report(idx); >> +} >> + > > Getting back to my suggestion from earlier today. It might make sense > to not bother with the PAGE_SHIFT or PAGE_SIZE multiplication if you > just record everything in VIRTIO_BALLOON_PAGES intead of using the > actual address and size. I think I prefer "addr + size". > > Same comment here. Make this array a part of virtio_balloon and you > don't have to free it. > >> +static const struct page_hinting_cb hcb = { >> + .prepare = page_hinting_prepare, >> + .hint_pages = hint_pages, >> + .cleanup = page_hinting_cleanup, >> + .max_pages = VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, >> +}; > > With the above changes prepare and cleanup can be dropped. +1 > >> +#endif >> + >> static u32 page_to_balloon_pfn(struct page *page) >> { >> unsigned long pfn = page_to_pfn(page); >> @@ -488,6 +574,7 @@ static int init_vqs(struct virtio_balloon *vb) >> names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate"; >> names[VIRTIO_BALLOON_VQ_STATS] = NULL; >> names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; >> + names[VIRTIO_BALLOON_VQ_HINTING] = NULL; >> >> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { >> names[VIRTIO_BALLOON_VQ_STATS] = "stats"; >> @@ -499,11 +586,18 @@ static int init_vqs(struct virtio_balloon *vb) >> callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; >> } >> >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { >> + names[VIRTIO_BALLOON_VQ_HINTING] = "hinting_vq"; >> + callbacks[VIRTIO_BALLOON_VQ_HINTING] = NULL; >> + } >> err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, >> vqs, callbacks, names, NULL, NULL); >> if (err) >> return err; >> >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) >> + vb->hinting_vq = vqs[VIRTIO_BALLOON_VQ_HINTING]; >> + >> vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE]; >> vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE]; >> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { >> @@ -942,6 +1036,14 @@ static int virtballoon_probe(struct virtio_device *vdev) >> if (err) >> goto out_del_balloon_wq; >> } >> + >> +#ifdef CONFIG_PAGE_HINTING >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) && >> + page_hinting_flag) { >> + hvb = vb; >> + page_hinting_enable(&hcb); >> + } >> +#endif >> virtio_device_ready(vdev); >> >> if (towards_target(vb)) >> @@ -989,6 +1091,12 @@ static void virtballoon_remove(struct virtio_device *vdev) >> destroy_workqueue(vb->balloon_wq); >> } >> >> +#ifdef CONFIG_PAGE_HINTING >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { Nitesh, you should only disable if you actually enabled it (page_hinting_flag).
On 6/3/19 6:38 PM, Alexander Duyck wrote: > On Mon, Jun 3, 2019 at 10:04 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: >> Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the >> host. If it is available and page_hinting_flag is set to true, page_hinting >> is enabled and its callbacks are configured along with the max_pages count >> which indicates the maximum number of pages that can be isolated and hinted >> at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are >> reported. To prevent any false OOM max_pages count is set to 16. >> >> By default page_hinting feature is enabled and gets loaded as soon >> as the virtio-balloon driver is loaded. However, it could be disabled >> by writing the page_hinting_flag which is a virtio-balloon parameter. >> >> Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> >> --- >> drivers/virtio/virtio_balloon.c | 112 +++++++++++++++++++++++++++- >> include/uapi/linux/virtio_balloon.h | 14 ++++ >> 2 files changed, 125 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c >> index f19061b585a4..40f09ea31643 100644 >> --- a/drivers/virtio/virtio_balloon.c >> +++ b/drivers/virtio/virtio_balloon.c >> @@ -31,6 +31,7 @@ >> #include <linux/mm.h> >> #include <linux/mount.h> >> #include <linux/magic.h> >> +#include <linux/page_hinting.h> >> >> /* >> * Balloon device works in 4K page units. So each page is pointed to by >> @@ -48,6 +49,7 @@ >> /* The size of a free page block in bytes */ >> #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ >> (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) >> +#define VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES 16 >> >> #ifdef CONFIG_BALLOON_COMPACTION >> static struct vfsmount *balloon_mnt; >> @@ -58,6 +60,7 @@ enum virtio_balloon_vq { >> VIRTIO_BALLOON_VQ_DEFLATE, >> VIRTIO_BALLOON_VQ_STATS, >> VIRTIO_BALLOON_VQ_FREE_PAGE, >> + VIRTIO_BALLOON_VQ_HINTING, >> VIRTIO_BALLOON_VQ_MAX >> }; >> >> @@ -67,7 +70,8 @@ enum virtio_balloon_config_read { >> >> struct virtio_balloon { >> struct virtio_device *vdev; >> - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; >> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, >> + *hinting_vq; >> >> /* Balloon's own wq for cpu-intensive work items */ >> struct workqueue_struct *balloon_wq; >> @@ -125,6 +129,9 @@ struct virtio_balloon { >> >> /* To register a shrinker to shrink memory upon memory pressure */ >> struct shrinker shrinker; >> + >> + /* object pointing at the array of isolated pages ready for hinting */ >> + struct hinting_data *hinting_arr; > Just make this an array of size VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES. > It will save a bunch of complexity later. Make sense. >> }; >> >> static struct virtio_device_id id_table[] = { >> @@ -132,6 +139,85 @@ static struct virtio_device_id id_table[] = { >> { 0 }, >> }; >> >> +#ifdef CONFIG_PAGE_HINTING > Instead of having CONFIG_PAGE_HINTING enable this, maybe we should > have virtio-balloon enable CONFIG_PAGE_HINTING. > >> +struct virtio_balloon *hvb; >> +bool page_hinting_flag = true; >> +module_param(page_hinting_flag, bool, 0444); >> +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); >> + >> +static bool virtqueue_kick_sync(struct virtqueue *vq) >> +{ >> + u32 len; >> + >> + if (likely(virtqueue_kick(vq))) { >> + while (!virtqueue_get_buf(vq, &len) && >> + !virtqueue_is_broken(vq)) >> + cpu_relax(); >> + return true; > Is this a synchronous setup? Yes. > It seems kind of wasteful to have a > thread busy waiting here like this. It might make more sense to just > make this work like the other balloon queues and have a wait event > with a wake up in the interrupt handler for the queue. I can do that. I may have to use a flag or something else to page_hinting.c as well to ensure that no other bitmap scanning is initiated until then. > >> + } >> + return false; >> +} >> + >> +static void page_hinting_report(int entries) >> +{ >> + struct scatterlist sg; >> + struct virtqueue *vq = hvb->hinting_vq; >> + int err = 0; >> + struct hinting_data *hint_req; >> + u64 gpaddr; >> + >> + hint_req = kmalloc(sizeof(*hint_req), GFP_KERNEL); >> + if (!hint_req) >> + return; > Why do we need another allocation here? Couldn't you just allocate > hint_req on the stack and then use that? I think we might be doing too > much here. All this really needs to look like is something along the > lines of tell_host() minus the wait_event. > >> + gpaddr = virt_to_phys(hvb->hinting_arr); >> + hint_req->phys_addr = cpu_to_virtio64(hvb->vdev, gpaddr); >> + hint_req->size = cpu_to_virtio32(hvb->vdev, entries); >> + sg_init_one(&sg, hint_req, sizeof(*hint_req)); >> + err = virtqueue_add_outbuf(vq, &sg, 1, hint_req, GFP_KERNEL); >> + if (!err) >> + virtqueue_kick_sync(hvb->hinting_vq); >> + >> + kfree(hint_req); >> +} >> + >> +int page_hinting_prepare(void) >> +{ >> + hvb->hinting_arr = kmalloc_array(VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, >> + sizeof(*hvb->hinting_arr), GFP_KERNEL); >> + if (!hvb->hinting_arr) >> + return -ENOMEM; >> + return 0; >> +} >> + > Why make the hinting_arr a dynamic allocation? You should probably > just make it a static array within the virtio_balloon structure. Then > you don't have the risk of an allocation failing and messing up the > hints. I agree. >> +void hint_pages(struct list_head *pages) >> +{ >> + struct page *page, *next; >> + unsigned long pfn; >> + int idx = 0, order; >> + >> + list_for_each_entry_safe(page, next, pages, lru) { >> + pfn = page_to_pfn(page); >> + order = page_private(page); >> + hvb->hinting_arr[idx].phys_addr = pfn << PAGE_SHIFT; >> + hvb->hinting_arr[idx].size = (1 << order) * PAGE_SIZE; >> + idx++; >> + } >> + page_hinting_report(idx); >> +} >> + > Getting back to my suggestion from earlier today. It might make sense > to not bother with the PAGE_SHIFT or PAGE_SIZE multiplication if you > just record everything in VIRTIO_BALLOON_PAGES intead of using the > actual address and size. > >> +void page_hinting_cleanup(void) >> +{ >> + kfree(hvb->hinting_arr); >> +} >> + > Same comment here. Make this array a part of virtio_balloon and you > don't have to free it. +1 > >> +static const struct page_hinting_cb hcb = { >> + .prepare = page_hinting_prepare, >> + .hint_pages = hint_pages, >> + .cleanup = page_hinting_cleanup, >> + .max_pages = VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, >> +}; > With the above changes prepare and cleanup can be dropped. > >> +#endif >> + >> static u32 page_to_balloon_pfn(struct page *page) >> { >> unsigned long pfn = page_to_pfn(page); >> @@ -488,6 +574,7 @@ static int init_vqs(struct virtio_balloon *vb) >> names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate"; >> names[VIRTIO_BALLOON_VQ_STATS] = NULL; >> names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; >> + names[VIRTIO_BALLOON_VQ_HINTING] = NULL; >> >> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { >> names[VIRTIO_BALLOON_VQ_STATS] = "stats"; >> @@ -499,11 +586,18 @@ static int init_vqs(struct virtio_balloon *vb) >> callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; >> } >> >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { >> + names[VIRTIO_BALLOON_VQ_HINTING] = "hinting_vq"; >> + callbacks[VIRTIO_BALLOON_VQ_HINTING] = NULL; >> + } >> err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, >> vqs, callbacks, names, NULL, NULL); >> if (err) >> return err; >> >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) >> + vb->hinting_vq = vqs[VIRTIO_BALLOON_VQ_HINTING]; >> + >> vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE]; >> vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE]; >> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { >> @@ -942,6 +1036,14 @@ static int virtballoon_probe(struct virtio_device *vdev) >> if (err) >> goto out_del_balloon_wq; >> } >> + >> +#ifdef CONFIG_PAGE_HINTING >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) && >> + page_hinting_flag) { >> + hvb = vb; >> + page_hinting_enable(&hcb); >> + } >> +#endif >> virtio_device_ready(vdev); >> >> if (towards_target(vb)) >> @@ -989,6 +1091,12 @@ static void virtballoon_remove(struct virtio_device *vdev) >> destroy_workqueue(vb->balloon_wq); >> } >> >> +#ifdef CONFIG_PAGE_HINTING >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { >> + hvb = NULL; >> + page_hinting_disable(); >> + } >> +#endif >> remove_common(vb); >> #ifdef CONFIG_BALLOON_COMPACTION >> if (vb->vb_dev_info.inode) >> @@ -1043,8 +1151,10 @@ static unsigned int features[] = { >> VIRTIO_BALLOON_F_MUST_TELL_HOST, >> VIRTIO_BALLOON_F_STATS_VQ, >> VIRTIO_BALLOON_F_DEFLATE_ON_OOM, >> + VIRTIO_BALLOON_F_HINTING, >> VIRTIO_BALLOON_F_FREE_PAGE_HINT, >> VIRTIO_BALLOON_F_PAGE_POISON, >> + VIRTIO_BALLOON_F_HINTING, >> }; >> >> static struct virtio_driver virtio_balloon_driver = { >> diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h >> index a1966cd7b677..25e4f817c660 100644 >> --- a/include/uapi/linux/virtio_balloon.h >> +++ b/include/uapi/linux/virtio_balloon.h >> @@ -29,6 +29,7 @@ >> #include <linux/virtio_types.h> >> #include <linux/virtio_ids.h> >> #include <linux/virtio_config.h> >> +#include <linux/page_hinting.h> >> >> /* The feature bitmap for virtio balloon */ >> #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */ >> @@ -36,6 +37,7 @@ >> #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */ >> #define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */ >> #define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */ >> +#define VIRTIO_BALLOON_F_HINTING 5 /* Page hinting virtqueue */ >> >> /* Size of a PFN in the balloon interface. */ >> #define VIRTIO_BALLOON_PFN_SHIFT 12 >> @@ -108,4 +110,16 @@ struct virtio_balloon_stat { >> __virtio64 val; >> } __attribute__((packed)); >> >> +#ifdef CONFIG_PAGE_HINTING >> +/* >> + * struct hinting_data- holds the information associated with hinting. >> + * @phys_add: physical address associated with a page or the array holding >> + * the array of isolated pages. >> + * @size: total size associated with the phys_addr. >> + */ >> +struct hinting_data { >> + __virtio64 phys_addr; >> + __virtio32 size; >> +}; > So in order to avoid errors this should either have > "__attribute__((packed))" added or it should be changed to a pair of > u32 or u64 values so that it will always be the same size regardless > of what platform it is built on. I will take a look at this. Thanks. >> +#endif >> #endif /* _LINUX_VIRTIO_BALLOON_H */ >> -- >> 2.21.0 >>
On 6/4/19 3:12 AM, David Hildenbrand wrote: > On 04.06.19 00:38, Alexander Duyck wrote: >> On Mon, Jun 3, 2019 at 10:04 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: >>> Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the >>> host. If it is available and page_hinting_flag is set to true, page_hinting >>> is enabled and its callbacks are configured along with the max_pages count >>> which indicates the maximum number of pages that can be isolated and hinted >>> at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are >>> reported. To prevent any false OOM max_pages count is set to 16. >>> >>> By default page_hinting feature is enabled and gets loaded as soon >>> as the virtio-balloon driver is loaded. However, it could be disabled >>> by writing the page_hinting_flag which is a virtio-balloon parameter. >>> >>> Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> >>> --- >>> drivers/virtio/virtio_balloon.c | 112 +++++++++++++++++++++++++++- >>> include/uapi/linux/virtio_balloon.h | 14 ++++ >>> 2 files changed, 125 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c >>> index f19061b585a4..40f09ea31643 100644 >>> --- a/drivers/virtio/virtio_balloon.c >>> +++ b/drivers/virtio/virtio_balloon.c >>> @@ -31,6 +31,7 @@ >>> #include <linux/mm.h> >>> #include <linux/mount.h> >>> #include <linux/magic.h> >>> +#include <linux/page_hinting.h> >>> >>> /* >>> * Balloon device works in 4K page units. So each page is pointed to by >>> @@ -48,6 +49,7 @@ >>> /* The size of a free page block in bytes */ >>> #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ >>> (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) >>> +#define VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES 16 >>> >>> #ifdef CONFIG_BALLOON_COMPACTION >>> static struct vfsmount *balloon_mnt; >>> @@ -58,6 +60,7 @@ enum virtio_balloon_vq { >>> VIRTIO_BALLOON_VQ_DEFLATE, >>> VIRTIO_BALLOON_VQ_STATS, >>> VIRTIO_BALLOON_VQ_FREE_PAGE, >>> + VIRTIO_BALLOON_VQ_HINTING, >>> VIRTIO_BALLOON_VQ_MAX >>> }; >>> >>> @@ -67,7 +70,8 @@ enum virtio_balloon_config_read { >>> >>> struct virtio_balloon { >>> struct virtio_device *vdev; >>> - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; >>> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, >>> + *hinting_vq; >>> >>> /* Balloon's own wq for cpu-intensive work items */ >>> struct workqueue_struct *balloon_wq; >>> @@ -125,6 +129,9 @@ struct virtio_balloon { >>> >>> /* To register a shrinker to shrink memory upon memory pressure */ >>> struct shrinker shrinker; >>> + >>> + /* object pointing at the array of isolated pages ready for hinting */ >>> + struct hinting_data *hinting_arr; >> Just make this an array of size VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES. >> It will save a bunch of complexity later. > +1 > > [...] >>> +struct virtio_balloon *hvb; >>> +bool page_hinting_flag = true; >>> +module_param(page_hinting_flag, bool, 0444); >>> +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); >>> + >>> +static bool virtqueue_kick_sync(struct virtqueue *vq) >>> +{ >>> + u32 len; >>> + >>> + if (likely(virtqueue_kick(vq))) { >>> + while (!virtqueue_get_buf(vq, &len) && >>> + !virtqueue_is_broken(vq)) >>> + cpu_relax(); >>> + return true; >> Is this a synchronous setup? It seems kind of wasteful to have a >> thread busy waiting here like this. It might make more sense to just >> make this work like the other balloon queues and have a wait event >> with a wake up in the interrupt handler for the queue. > +1 > > [...] > >>> + gpaddr = virt_to_phys(hvb->hinting_arr); >>> + hint_req->phys_addr = cpu_to_virtio64(hvb->vdev, gpaddr); >>> + hint_req->size = cpu_to_virtio32(hvb->vdev, entries); >>> + sg_init_one(&sg, hint_req, sizeof(*hint_req)); >>> + err = virtqueue_add_outbuf(vq, &sg, 1, hint_req, GFP_KERNEL); >>> + if (!err) >>> + virtqueue_kick_sync(hvb->hinting_vq); >>> + >>> + kfree(hint_req); >>> +} >>> + >>> +int page_hinting_prepare(void) >>> +{ >>> + hvb->hinting_arr = kmalloc_array(VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, >>> + sizeof(*hvb->hinting_arr), GFP_KERNEL); >>> + if (!hvb->hinting_arr) >>> + return -ENOMEM; >>> + return 0; >>> +} >>> + >> Why make the hinting_arr a dynamic allocation? You should probably >> just make it a static array within the virtio_balloon structure. Then >> you don't have the risk of an allocation failing and messing up the >> hints. > +1 > >>> +void hint_pages(struct list_head *pages) >>> +{ >>> + struct page *page, *next; >>> + unsigned long pfn; >>> + int idx = 0, order; >>> + >>> + list_for_each_entry_safe(page, next, pages, lru) { >>> + pfn = page_to_pfn(page); >>> + order = page_private(page); >>> + hvb->hinting_arr[idx].phys_addr = pfn << PAGE_SHIFT; >>> + hvb->hinting_arr[idx].size = (1 << order) * PAGE_SIZE; >>> + idx++; >>> + } >>> + page_hinting_report(idx); >>> +} >>> + >> Getting back to my suggestion from earlier today. It might make sense >> to not bother with the PAGE_SHIFT or PAGE_SIZE multiplication if you >> just record everything in VIRTIO_BALLOON_PAGES intead of using the >> actual address and size. > I think I prefer "addr + size". > >> Same comment here. Make this array a part of virtio_balloon and you >> don't have to free it. >> >>> +static const struct page_hinting_cb hcb = { >>> + .prepare = page_hinting_prepare, >>> + .hint_pages = hint_pages, >>> + .cleanup = page_hinting_cleanup, >>> + .max_pages = VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, >>> +}; >> With the above changes prepare and cleanup can be dropped. > +1 > >>> +#endif >>> + >>> static u32 page_to_balloon_pfn(struct page *page) >>> { >>> unsigned long pfn = page_to_pfn(page); >>> @@ -488,6 +574,7 @@ static int init_vqs(struct virtio_balloon *vb) >>> names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate"; >>> names[VIRTIO_BALLOON_VQ_STATS] = NULL; >>> names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; >>> + names[VIRTIO_BALLOON_VQ_HINTING] = NULL; >>> >>> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { >>> names[VIRTIO_BALLOON_VQ_STATS] = "stats"; >>> @@ -499,11 +586,18 @@ static int init_vqs(struct virtio_balloon *vb) >>> callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; >>> } >>> >>> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { >>> + names[VIRTIO_BALLOON_VQ_HINTING] = "hinting_vq"; >>> + callbacks[VIRTIO_BALLOON_VQ_HINTING] = NULL; >>> + } >>> err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, >>> vqs, callbacks, names, NULL, NULL); >>> if (err) >>> return err; >>> >>> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) >>> + vb->hinting_vq = vqs[VIRTIO_BALLOON_VQ_HINTING]; >>> + >>> vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE]; >>> vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE]; >>> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { >>> @@ -942,6 +1036,14 @@ static int virtballoon_probe(struct virtio_device *vdev) >>> if (err) >>> goto out_del_balloon_wq; >>> } >>> + >>> +#ifdef CONFIG_PAGE_HINTING >>> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) && >>> + page_hinting_flag) { >>> + hvb = vb; >>> + page_hinting_enable(&hcb); >>> + } >>> +#endif >>> virtio_device_ready(vdev); >>> >>> if (towards_target(vb)) >>> @@ -989,6 +1091,12 @@ static void virtballoon_remove(struct virtio_device *vdev) >>> destroy_workqueue(vb->balloon_wq); >>> } >>> >>> +#ifdef CONFIG_PAGE_HINTING >>> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { > Nitesh, you should only disable if you actually enabled it > (page_hinting_flag). +1, thanks. > >
On Mon, Jun 3, 2019 at 10:04 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: > > Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the > host. If it is available and page_hinting_flag is set to true, page_hinting > is enabled and its callbacks are configured along with the max_pages count > which indicates the maximum number of pages that can be isolated and hinted > at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are > reported. To prevent any false OOM max_pages count is set to 16. > > By default page_hinting feature is enabled and gets loaded as soon > as the virtio-balloon driver is loaded. However, it could be disabled > by writing the page_hinting_flag which is a virtio-balloon parameter. > > Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> > --- > drivers/virtio/virtio_balloon.c | 112 +++++++++++++++++++++++++++- > include/uapi/linux/virtio_balloon.h | 14 ++++ > 2 files changed, 125 insertions(+), 1 deletion(-) <snip> > diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h > index a1966cd7b677..25e4f817c660 100644 > --- a/include/uapi/linux/virtio_balloon.h > +++ b/include/uapi/linux/virtio_balloon.h > @@ -29,6 +29,7 @@ > #include <linux/virtio_types.h> > #include <linux/virtio_ids.h> > #include <linux/virtio_config.h> > +#include <linux/page_hinting.h> So this include breaks the build and from what I can tell it isn't really needed. I deleted it in order to be able to build without warnings about the file not being included in UAPI. > /* The feature bitmap for virtio balloon */ > #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */ > @@ -36,6 +37,7 @@ > #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */ > #define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */ > #define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */ > +#define VIRTIO_BALLOON_F_HINTING 5 /* Page hinting virtqueue */ > > /* Size of a PFN in the balloon interface. */ > #define VIRTIO_BALLOON_PFN_SHIFT 12 > @@ -108,4 +110,16 @@ struct virtio_balloon_stat { > __virtio64 val; > } __attribute__((packed)); > > +#ifdef CONFIG_PAGE_HINTING > +/* > + * struct hinting_data- holds the information associated with hinting. > + * @phys_add: physical address associated with a page or the array holding > + * the array of isolated pages. > + * @size: total size associated with the phys_addr. > + */ > +struct hinting_data { > + __virtio64 phys_addr; > + __virtio32 size; > +}; > +#endif > #endif /* _LINUX_VIRTIO_BALLOON_H */ > -- > 2.21.0 >
On 6/4/19 12:33 PM, Alexander Duyck wrote: > On Mon, Jun 3, 2019 at 10:04 AM Nitesh Narayan Lal <nitesh@redhat.com> wrote: >> Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the >> host. If it is available and page_hinting_flag is set to true, page_hinting >> is enabled and its callbacks are configured along with the max_pages count >> which indicates the maximum number of pages that can be isolated and hinted >> at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are >> reported. To prevent any false OOM max_pages count is set to 16. >> >> By default page_hinting feature is enabled and gets loaded as soon >> as the virtio-balloon driver is loaded. However, it could be disabled >> by writing the page_hinting_flag which is a virtio-balloon parameter. >> >> Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> >> --- >> drivers/virtio/virtio_balloon.c | 112 +++++++++++++++++++++++++++- >> include/uapi/linux/virtio_balloon.h | 14 ++++ >> 2 files changed, 125 insertions(+), 1 deletion(-) > <snip> > >> diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h >> index a1966cd7b677..25e4f817c660 100644 >> --- a/include/uapi/linux/virtio_balloon.h >> +++ b/include/uapi/linux/virtio_balloon.h >> @@ -29,6 +29,7 @@ >> #include <linux/virtio_types.h> >> #include <linux/virtio_ids.h> >> #include <linux/virtio_config.h> >> +#include <linux/page_hinting.h> > So this include breaks the build and from what I can tell it isn't > really needed. I deleted it in order to be able to build without > warnings about the file not being included in UAPI. I agree here, it is not required any more. > >> /* The feature bitmap for virtio balloon */ >> #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */ >> @@ -36,6 +37,7 @@ >> #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */ >> #define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */ >> #define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */ >> +#define VIRTIO_BALLOON_F_HINTING 5 /* Page hinting virtqueue */ >> >> /* Size of a PFN in the balloon interface. */ >> #define VIRTIO_BALLOON_PFN_SHIFT 12 >> @@ -108,4 +110,16 @@ struct virtio_balloon_stat { >> __virtio64 val; >> } __attribute__((packed)); >> >> +#ifdef CONFIG_PAGE_HINTING >> +/* >> + * struct hinting_data- holds the information associated with hinting. >> + * @phys_add: physical address associated with a page or the array holding >> + * the array of isolated pages. >> + * @size: total size associated with the phys_addr. >> + */ >> +struct hinting_data { >> + __virtio64 phys_addr; >> + __virtio32 size; >> +}; >> +#endif >> #endif /* _LINUX_VIRTIO_BALLOON_H */ >> -- >> 2.21.0 >>
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index f19061b585a4..40f09ea31643 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -31,6 +31,7 @@ #include <linux/mm.h> #include <linux/mount.h> #include <linux/magic.h> +#include <linux/page_hinting.h> /* * Balloon device works in 4K page units. So each page is pointed to by @@ -48,6 +49,7 @@ /* The size of a free page block in bytes */ #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) +#define VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES 16 #ifdef CONFIG_BALLOON_COMPACTION static struct vfsmount *balloon_mnt; @@ -58,6 +60,7 @@ enum virtio_balloon_vq { VIRTIO_BALLOON_VQ_DEFLATE, VIRTIO_BALLOON_VQ_STATS, VIRTIO_BALLOON_VQ_FREE_PAGE, + VIRTIO_BALLOON_VQ_HINTING, VIRTIO_BALLOON_VQ_MAX }; @@ -67,7 +70,8 @@ enum virtio_balloon_config_read { struct virtio_balloon { struct virtio_device *vdev; - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, + *hinting_vq; /* Balloon's own wq for cpu-intensive work items */ struct workqueue_struct *balloon_wq; @@ -125,6 +129,9 @@ struct virtio_balloon { /* To register a shrinker to shrink memory upon memory pressure */ struct shrinker shrinker; + + /* object pointing at the array of isolated pages ready for hinting */ + struct hinting_data *hinting_arr; }; static struct virtio_device_id id_table[] = { @@ -132,6 +139,85 @@ static struct virtio_device_id id_table[] = { { 0 }, }; +#ifdef CONFIG_PAGE_HINTING +struct virtio_balloon *hvb; +bool page_hinting_flag = true; +module_param(page_hinting_flag, bool, 0444); +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); + +static bool virtqueue_kick_sync(struct virtqueue *vq) +{ + u32 len; + + if (likely(virtqueue_kick(vq))) { + while (!virtqueue_get_buf(vq, &len) && + !virtqueue_is_broken(vq)) + cpu_relax(); + return true; + } + return false; +} + +static void page_hinting_report(int entries) +{ + struct scatterlist sg; + struct virtqueue *vq = hvb->hinting_vq; + int err = 0; + struct hinting_data *hint_req; + u64 gpaddr; + + hint_req = kmalloc(sizeof(*hint_req), GFP_KERNEL); + if (!hint_req) + return; + gpaddr = virt_to_phys(hvb->hinting_arr); + hint_req->phys_addr = cpu_to_virtio64(hvb->vdev, gpaddr); + hint_req->size = cpu_to_virtio32(hvb->vdev, entries); + sg_init_one(&sg, hint_req, sizeof(*hint_req)); + err = virtqueue_add_outbuf(vq, &sg, 1, hint_req, GFP_KERNEL); + if (!err) + virtqueue_kick_sync(hvb->hinting_vq); + + kfree(hint_req); +} + +int page_hinting_prepare(void) +{ + hvb->hinting_arr = kmalloc_array(VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, + sizeof(*hvb->hinting_arr), GFP_KERNEL); + if (!hvb->hinting_arr) + return -ENOMEM; + return 0; +} + +void hint_pages(struct list_head *pages) +{ + struct page *page, *next; + unsigned long pfn; + int idx = 0, order; + + list_for_each_entry_safe(page, next, pages, lru) { + pfn = page_to_pfn(page); + order = page_private(page); + hvb->hinting_arr[idx].phys_addr = pfn << PAGE_SHIFT; + hvb->hinting_arr[idx].size = (1 << order) * PAGE_SIZE; + idx++; + } + page_hinting_report(idx); +} + +void page_hinting_cleanup(void) +{ + kfree(hvb->hinting_arr); +} + +static const struct page_hinting_cb hcb = { + .prepare = page_hinting_prepare, + .hint_pages = hint_pages, + .cleanup = page_hinting_cleanup, + .max_pages = VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES, +}; +#endif + static u32 page_to_balloon_pfn(struct page *page) { unsigned long pfn = page_to_pfn(page); @@ -488,6 +574,7 @@ static int init_vqs(struct virtio_balloon *vb) names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate"; names[VIRTIO_BALLOON_VQ_STATS] = NULL; names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; + names[VIRTIO_BALLOON_VQ_HINTING] = NULL; if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { names[VIRTIO_BALLOON_VQ_STATS] = "stats"; @@ -499,11 +586,18 @@ static int init_vqs(struct virtio_balloon *vb) callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; } + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { + names[VIRTIO_BALLOON_VQ_HINTING] = "hinting_vq"; + callbacks[VIRTIO_BALLOON_VQ_HINTING] = NULL; + } err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, vqs, callbacks, names, NULL, NULL); if (err) return err; + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) + vb->hinting_vq = vqs[VIRTIO_BALLOON_VQ_HINTING]; + vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE]; vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE]; if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { @@ -942,6 +1036,14 @@ static int virtballoon_probe(struct virtio_device *vdev) if (err) goto out_del_balloon_wq; } + +#ifdef CONFIG_PAGE_HINTING + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) && + page_hinting_flag) { + hvb = vb; + page_hinting_enable(&hcb); + } +#endif virtio_device_ready(vdev); if (towards_target(vb)) @@ -989,6 +1091,12 @@ static void virtballoon_remove(struct virtio_device *vdev) destroy_workqueue(vb->balloon_wq); } +#ifdef CONFIG_PAGE_HINTING + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { + hvb = NULL; + page_hinting_disable(); + } +#endif remove_common(vb); #ifdef CONFIG_BALLOON_COMPACTION if (vb->vb_dev_info.inode) @@ -1043,8 +1151,10 @@ static unsigned int features[] = { VIRTIO_BALLOON_F_MUST_TELL_HOST, VIRTIO_BALLOON_F_STATS_VQ, VIRTIO_BALLOON_F_DEFLATE_ON_OOM, + VIRTIO_BALLOON_F_HINTING, VIRTIO_BALLOON_F_FREE_PAGE_HINT, VIRTIO_BALLOON_F_PAGE_POISON, + VIRTIO_BALLOON_F_HINTING, }; static struct virtio_driver virtio_balloon_driver = { diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h index a1966cd7b677..25e4f817c660 100644 --- a/include/uapi/linux/virtio_balloon.h +++ b/include/uapi/linux/virtio_balloon.h @@ -29,6 +29,7 @@ #include <linux/virtio_types.h> #include <linux/virtio_ids.h> #include <linux/virtio_config.h> +#include <linux/page_hinting.h> /* The feature bitmap for virtio balloon */ #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */ @@ -36,6 +37,7 @@ #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */ #define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */ #define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */ +#define VIRTIO_BALLOON_F_HINTING 5 /* Page hinting virtqueue */ /* Size of a PFN in the balloon interface. */ #define VIRTIO_BALLOON_PFN_SHIFT 12 @@ -108,4 +110,16 @@ struct virtio_balloon_stat { __virtio64 val; } __attribute__((packed)); +#ifdef CONFIG_PAGE_HINTING +/* + * struct hinting_data- holds the information associated with hinting. + * @phys_add: physical address associated with a page or the array holding + * the array of isolated pages. + * @size: total size associated with the phys_addr. + */ +struct hinting_data { + __virtio64 phys_addr; + __virtio32 size; +}; +#endif #endif /* _LINUX_VIRTIO_BALLOON_H */
Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the host. If it is available and page_hinting_flag is set to true, page_hinting is enabled and its callbacks are configured along with the max_pages count which indicates the maximum number of pages that can be isolated and hinted at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are reported. To prevent any false OOM max_pages count is set to 16. By default page_hinting feature is enabled and gets loaded as soon as the virtio-balloon driver is loaded. However, it could be disabled by writing the page_hinting_flag which is a virtio-balloon parameter. Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> --- drivers/virtio/virtio_balloon.c | 112 +++++++++++++++++++++++++++- include/uapi/linux/virtio_balloon.h | 14 ++++ 2 files changed, 125 insertions(+), 1 deletion(-)