| Message ID | 20201120064325.34492-18-songmuchun@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Free some vmemmap pages of hugetlb page | expand |
On Fri 20-11-20 14:43:21, Muchun Song wrote: > Add a kernel parameter hugetlb_free_vmemmap to disable the feature of > freeing unused vmemmap pages associated with each hugetlb page on boot. As replied to the config patch. This is fine but I would argue that the default should be flipped. Saving memory is nice but it comes with overhead and therefore should be an opt-in. The config option should only guard compile time dependencies not a user choice. > Signed-off-by: Muchun Song <songmuchun@bytedance.com> > --- > Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++ > Documentation/admin-guide/mm/hugetlbpage.rst | 3 +++ > mm/hugetlb_vmemmap.c | 21 +++++++++++++++++++++ > 3 files changed, 33 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 5debfe238027..ccf07293cb63 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -1551,6 +1551,15 @@ > Documentation/admin-guide/mm/hugetlbpage.rst. > Format: size[KMG] > > + hugetlb_free_vmemmap= > + [KNL] When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, > + this controls freeing unused vmemmap pages associated > + with each HugeTLB page. > + Format: { on (default) | off } > + > + on: enable the feature > + off: disable the feature > + > hung_task_panic= > [KNL] Should the hung task detector generate panics. > Format: 0 | 1 > diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst > index f7b1c7462991..7d6129ee97dd 100644 > --- a/Documentation/admin-guide/mm/hugetlbpage.rst > +++ b/Documentation/admin-guide/mm/hugetlbpage.rst > @@ -145,6 +145,9 @@ default_hugepagesz > > will all result in 256 2M huge pages being allocated. Valid default > huge page size is architecture dependent. > +hugetlb_free_vmemmap > + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this disables freeing > + unused vmemmap pages associated each HugeTLB page. > > When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages`` > indicates the current number of pre-allocated huge pages of the default size. > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > index 3629165d8158..c958699d1393 100644 > --- a/mm/hugetlb_vmemmap.c > +++ b/mm/hugetlb_vmemmap.c > @@ -144,6 +144,22 @@ static inline bool vmemmap_pmd_huge(pmd_t *pmd) > } > #endif > > +static bool hugetlb_free_vmemmap_disabled __initdata; > + > +static int __init early_hugetlb_free_vmemmap_param(char *buf) > +{ > + if (!buf) > + return -EINVAL; > + > + if (!strcmp(buf, "off")) > + hugetlb_free_vmemmap_disabled = true; > + else if (strcmp(buf, "on")) > + return -EINVAL; > + > + return 0; > +} > +early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param); > + > static inline unsigned int vmemmap_pages_per_hpage(struct hstate *h) > { > return free_vmemmap_pages_per_hpage(h) + RESERVE_VMEMMAP_NR; > @@ -541,6 +557,11 @@ void __init hugetlb_vmemmap_init(struct hstate *h) > unsigned int order = huge_page_order(h); > unsigned int vmemmap_pages; > > + if (hugetlb_free_vmemmap_disabled) { > + pr_info("disable free vmemmap pages for %s\n", h->name); > + return; > + } > + > vmemmap_pages = ((1 << order) * sizeof(struct page)) >> PAGE_SHIFT; > /* > * The head page and the first tail page are not to be freed to buddy > -- > 2.11.0
On Fri, Nov 20, 2020 at 4:22 PM Michal Hocko <mhocko@suse.com> wrote: > > On Fri 20-11-20 14:43:21, Muchun Song wrote: > > Add a kernel parameter hugetlb_free_vmemmap to disable the feature of > > freeing unused vmemmap pages associated with each hugetlb page on boot. > > As replied to the config patch. This is fine but I would argue that the > default should be flipped. Saving memory is nice but it comes with > overhead and therefore should be an opt-in. The config option should > only guard compile time dependencies not a user choice. Got it. The default will be flipped in the next version. Thanks. > > > Signed-off-by: Muchun Song <songmuchun@bytedance.com> > > --- > > Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++ > > Documentation/admin-guide/mm/hugetlbpage.rst | 3 +++ > > mm/hugetlb_vmemmap.c | 21 +++++++++++++++++++++ > > 3 files changed, 33 insertions(+) > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > > index 5debfe238027..ccf07293cb63 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -1551,6 +1551,15 @@ > > Documentation/admin-guide/mm/hugetlbpage.rst. > > Format: size[KMG] > > > > + hugetlb_free_vmemmap= > > + [KNL] When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, > > + this controls freeing unused vmemmap pages associated > > + with each HugeTLB page. > > + Format: { on (default) | off } > > + > > + on: enable the feature > > + off: disable the feature > > + > > hung_task_panic= > > [KNL] Should the hung task detector generate panics. > > Format: 0 | 1 > > diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst > > index f7b1c7462991..7d6129ee97dd 100644 > > --- a/Documentation/admin-guide/mm/hugetlbpage.rst > > +++ b/Documentation/admin-guide/mm/hugetlbpage.rst > > @@ -145,6 +145,9 @@ default_hugepagesz > > > > will all result in 256 2M huge pages being allocated. Valid default > > huge page size is architecture dependent. > > +hugetlb_free_vmemmap > > + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this disables freeing > > + unused vmemmap pages associated each HugeTLB page. > > > > When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages`` > > indicates the current number of pre-allocated huge pages of the default size. > > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > > index 3629165d8158..c958699d1393 100644 > > --- a/mm/hugetlb_vmemmap.c > > +++ b/mm/hugetlb_vmemmap.c > > @@ -144,6 +144,22 @@ static inline bool vmemmap_pmd_huge(pmd_t *pmd) > > } > > #endif > > > > +static bool hugetlb_free_vmemmap_disabled __initdata; > > + > > +static int __init early_hugetlb_free_vmemmap_param(char *buf) > > +{ > > + if (!buf) > > + return -EINVAL; > > + > > + if (!strcmp(buf, "off")) > > + hugetlb_free_vmemmap_disabled = true; > > + else if (strcmp(buf, "on")) > > + return -EINVAL; > > + > > + return 0; > > +} > > +early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param); > > + > > static inline unsigned int vmemmap_pages_per_hpage(struct hstate *h) > > { > > return free_vmemmap_pages_per_hpage(h) + RESERVE_VMEMMAP_NR; > > @@ -541,6 +557,11 @@ void __init hugetlb_vmemmap_init(struct hstate *h) > > unsigned int order = huge_page_order(h); > > unsigned int vmemmap_pages; > > > > + if (hugetlb_free_vmemmap_disabled) { > > + pr_info("disable free vmemmap pages for %s\n", h->name); > > + return; > > + } > > + > > vmemmap_pages = ((1 << order) * sizeof(struct page)) >> PAGE_SHIFT; > > /* > > * The head page and the first tail page are not to be freed to buddy > > -- > > 2.11.0 > > -- > Michal Hocko > SUSE Labs
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 5debfe238027..ccf07293cb63 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1551,6 +1551,15 @@ Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] + hugetlb_free_vmemmap= + [KNL] When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, + this controls freeing unused vmemmap pages associated + with each HugeTLB page. + Format: { on (default) | off } + + on: enable the feature + off: disable the feature + hung_task_panic= [KNL] Should the hung task detector generate panics. Format: 0 | 1 diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst index f7b1c7462991..7d6129ee97dd 100644 --- a/Documentation/admin-guide/mm/hugetlbpage.rst +++ b/Documentation/admin-guide/mm/hugetlbpage.rst @@ -145,6 +145,9 @@ default_hugepagesz will all result in 256 2M huge pages being allocated. Valid default huge page size is architecture dependent. +hugetlb_free_vmemmap + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this disables freeing + unused vmemmap pages associated each HugeTLB page. When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages`` indicates the current number of pre-allocated huge pages of the default size. diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 3629165d8158..c958699d1393 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -144,6 +144,22 @@ static inline bool vmemmap_pmd_huge(pmd_t *pmd) } #endif +static bool hugetlb_free_vmemmap_disabled __initdata; + +static int __init early_hugetlb_free_vmemmap_param(char *buf) +{ + if (!buf) + return -EINVAL; + + if (!strcmp(buf, "off")) + hugetlb_free_vmemmap_disabled = true; + else if (strcmp(buf, "on")) + return -EINVAL; + + return 0; +} +early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param); + static inline unsigned int vmemmap_pages_per_hpage(struct hstate *h) { return free_vmemmap_pages_per_hpage(h) + RESERVE_VMEMMAP_NR; @@ -541,6 +557,11 @@ void __init hugetlb_vmemmap_init(struct hstate *h) unsigned int order = huge_page_order(h); unsigned int vmemmap_pages; + if (hugetlb_free_vmemmap_disabled) { + pr_info("disable free vmemmap pages for %s\n", h->name); + return; + } + vmemmap_pages = ((1 << order) * sizeof(struct page)) >> PAGE_SHIFT; /* * The head page and the first tail page are not to be freed to buddy
Add a kernel parameter hugetlb_free_vmemmap to disable the feature of freeing unused vmemmap pages associated with each hugetlb page on boot. Signed-off-by: Muchun Song <songmuchun@bytedance.com> --- Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++ Documentation/admin-guide/mm/hugetlbpage.rst | 3 +++ mm/hugetlb_vmemmap.c | 21 +++++++++++++++++++++ 3 files changed, 33 insertions(+)