| Message ID | 20211220085649.8196-14-songmuchun@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Optimize list lru memory consumption | expand |
Hi, On 20.12.2021 10.56, Muchun Song wrote: > There are two idrs being used by memory cgroup, one is for kmem ID, > another is for memory cgroup ID. The maximum ID of both is 64Ki. > Both of them can limit the total number of memory cgroups. Actually, > we can reuse memory cgroup ID for kmem ID to simplify the code. > > Signed-off-by: Muchun Song <songmuchun@bytedance.com> > --- > include/linux/memcontrol.h | 1 + > mm/memcontrol.c | 46 ++++++++-------------------------------------- > 2 files changed, 9 insertions(+), 38 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 3fc437162add..7b472f805d77 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -56,6 +56,7 @@ struct mem_cgroup_reclaim_cookie { > #ifdef CONFIG_MEMCG > > #define MEM_CGROUP_ID_SHIFT 16 > +#define MEM_CGROUP_ID_MIN 1 > #define MEM_CGROUP_ID_MAX USHRT_MAX > > struct mem_cgroup_id { > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 28d6d2564f9d..04f75055f518 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -348,23 +348,6 @@ static void memcg_reparent_objcgs(struct mem_cgroup *memcg, > } > > /* > - * This will be used as a shrinker list's index. > - * The main reason for not using cgroup id for this: > - * this works better in sparse environments, where we have a lot of memcgs, > - * but only a few kmem-limited. > - */ > -static DEFINE_IDA(memcg_cache_ida); > - > -/* > - * MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get > - * this constant directly from cgroup, but it is understandable that this is > - * better kept as an internal representation in cgroup.c. In any case, the > - * cgrp_id space is not getting any smaller, and we don't have to necessarily > - * increase ours as well if it increases. > - */ > -#define MEMCG_CACHES_MAX_SIZE MEM_CGROUP_ID_MAX > - > -/* > * A lot of the calls to the cache allocation functions are expected to be > * inlined by the compiler. Since the calls to memcg_slab_pre_alloc_hook() are > * conditional to this static branch, we'll have to allow modules that does > @@ -3528,10 +3511,12 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css, > } > > #ifdef CONFIG_MEMCG_KMEM > +#define MEM_CGROUP_KMEM_ID_MIN -1 Maybe #define MEM_CGROUP_KMEM_ID_MIN 0 to be the first allocated id, so MEM_CGROUP_ID_DIFF is 1, not 2 > +#define MEM_CGROUP_ID_DIFF (MEM_CGROUP_ID_MIN - MEM_CGROUP_KMEM_ID_MIN) > + > static int memcg_online_kmem(struct mem_cgroup *memcg) > { > struct obj_cgroup *objcg; > - int memcg_id; > > if (cgroup_memory_nokmem) > return 0; > @@ -3539,22 +3524,16 @@ static int memcg_online_kmem(struct mem_cgroup *memcg) > if (unlikely(mem_cgroup_is_root(memcg))) > return 0; > > - memcg_id = ida_alloc_max(&memcg_cache_ida, MEMCG_CACHES_MAX_SIZE - 1, > - GFP_KERNEL); > - if (memcg_id < 0) > - return memcg_id; > - > objcg = obj_cgroup_alloc(); > - if (!objcg) { > - ida_free(&memcg_cache_ida, memcg_id); > + if (!objcg) > return -ENOMEM; > - } > + > objcg->memcg = memcg; > rcu_assign_pointer(memcg->objcg, objcg); > > static_branch_enable(&memcg_kmem_enabled_key); > > - memcg->kmemcg_id = memcg_id; > + memcg->kmemcg_id = memcg->id.id - MEM_CGROUP_ID_DIFF; > > return 0; > } > @@ -3562,7 +3541,6 @@ static int memcg_online_kmem(struct mem_cgroup *memcg) > static void memcg_offline_kmem(struct mem_cgroup *memcg) > { > struct mem_cgroup *parent; > - int kmemcg_id; > > if (cgroup_memory_nokmem) > return; > @@ -3577,20 +3555,12 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg) > memcg_reparent_objcgs(memcg, parent); > > /* > - * memcg_reparent_list_lrus() can change memcg->kmemcg_id. > - * Cache it to local @kmemcg_id. > - */ > - kmemcg_id = memcg->kmemcg_id; > - > - /* > * After we have finished memcg_reparent_objcgs(), all list_lrus > * corresponding to this cgroup are guaranteed to remain empty. > * The ordering is imposed by list_lru_node->lock taken by > * memcg_reparent_list_lrus(). > */ > memcg_reparent_list_lrus(memcg, parent); > - > - ida_free(&memcg_cache_ida, kmemcg_id); > } > #else > static int memcg_online_kmem(struct mem_cgroup *memcg) > @@ -5043,7 +5013,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void) > return ERR_PTR(error); > > memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL, > - 1, MEM_CGROUP_ID_MAX, > + MEM_CGROUP_ID_MIN, MEM_CGROUP_ID_MAX, > GFP_KERNEL); > if (memcg->id.id < 0) { > error = memcg->id.id; > @@ -5071,7 +5041,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void) > spin_lock_init(&memcg->event_list_lock); > memcg->socket_pressure = jiffies; > #ifdef CONFIG_MEMCG_KMEM > - memcg->kmemcg_id = -1; > + memcg->kmemcg_id = MEM_CGROUP_KMEM_ID_MIN; > INIT_LIST_HEAD(&memcg->objcg_list); > #endif > #ifdef CONFIG_CGROUP_WRITEBACK
On Mon, Dec 20, 2021 at 04:56:46PM +0800, Muchun Song <songmuchun@bytedance.com> wrote: > There are two idrs being used by memory cgroup, one is for kmem ID, > another is for memory cgroup ID. The maximum ID of both is 64Ki. > Both of them can limit the total number of memory cgroups. > Actually, we can reuse memory cgroup ID for kmem ID to simplify the > code. An interesting improvement. I'm a bit dense -- what's the purpose the MEM_CGROUP_ID_DIFF offset? Couldn't this deduplication be extended to only use mem_cgroup.id.id instead of mem_cgroup.kmemcg_id? (With a boolean telling whether kmem accounting is active.) Thanks, Michal
On Thu, Jan 6, 2022 at 1:03 AM Michal Koutný <mkoutny@suse.com> wrote: > > On Mon, Dec 20, 2021 at 04:56:46PM +0800, Muchun Song <songmuchun@bytedance.com> wrote: > > There are two idrs being used by memory cgroup, one is for kmem ID, > > another is for memory cgroup ID. The maximum ID of both is 64Ki. > > Both of them can limit the total number of memory cgroups. > > Actually, we can reuse memory cgroup ID for kmem ID to simplify the > > code. > > An interesting improvement. > > I'm a bit dense -- what's the purpose the MEM_CGROUP_ID_DIFF offset? Hi Michal and Mika, MEM_CGROUP_ID_DIFF is introduced to be consistent with before that kmem ID starts with -1 and has no holes. Actually, it can be dropped and make memcg->kmemcg_id equal to memcg->id.id directly. > Couldn't this deduplication be extended to only use mem_cgroup.id.id > instead of mem_cgroup.kmemcg_id? (With a boolean telling whether kmem > accounting is active.) > Not easy to completely remove memcg->kmemcg_id since this filed will be used to sync list_lru reparenting which will change memcg->kmemcg_id to its parent's kmem ID (more details refers to memcg_drain_all_list_lrus() in patch 10 of this series). Thanks.
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 3fc437162add..7b472f805d77 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -56,6 +56,7 @@ struct mem_cgroup_reclaim_cookie { #ifdef CONFIG_MEMCG #define MEM_CGROUP_ID_SHIFT 16 +#define MEM_CGROUP_ID_MIN 1 #define MEM_CGROUP_ID_MAX USHRT_MAX struct mem_cgroup_id { diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 28d6d2564f9d..04f75055f518 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -348,23 +348,6 @@ static void memcg_reparent_objcgs(struct mem_cgroup *memcg, } /* - * This will be used as a shrinker list's index. - * The main reason for not using cgroup id for this: - * this works better in sparse environments, where we have a lot of memcgs, - * but only a few kmem-limited. - */ -static DEFINE_IDA(memcg_cache_ida); - -/* - * MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get - * this constant directly from cgroup, but it is understandable that this is - * better kept as an internal representation in cgroup.c. In any case, the - * cgrp_id space is not getting any smaller, and we don't have to necessarily - * increase ours as well if it increases. - */ -#define MEMCG_CACHES_MAX_SIZE MEM_CGROUP_ID_MAX - -/* * A lot of the calls to the cache allocation functions are expected to be * inlined by the compiler. Since the calls to memcg_slab_pre_alloc_hook() are * conditional to this static branch, we'll have to allow modules that does @@ -3528,10 +3511,12 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css, } #ifdef CONFIG_MEMCG_KMEM +#define MEM_CGROUP_KMEM_ID_MIN -1 +#define MEM_CGROUP_ID_DIFF (MEM_CGROUP_ID_MIN - MEM_CGROUP_KMEM_ID_MIN) + static int memcg_online_kmem(struct mem_cgroup *memcg) { struct obj_cgroup *objcg; - int memcg_id; if (cgroup_memory_nokmem) return 0; @@ -3539,22 +3524,16 @@ static int memcg_online_kmem(struct mem_cgroup *memcg) if (unlikely(mem_cgroup_is_root(memcg))) return 0; - memcg_id = ida_alloc_max(&memcg_cache_ida, MEMCG_CACHES_MAX_SIZE - 1, - GFP_KERNEL); - if (memcg_id < 0) - return memcg_id; - objcg = obj_cgroup_alloc(); - if (!objcg) { - ida_free(&memcg_cache_ida, memcg_id); + if (!objcg) return -ENOMEM; - } + objcg->memcg = memcg; rcu_assign_pointer(memcg->objcg, objcg); static_branch_enable(&memcg_kmem_enabled_key); - memcg->kmemcg_id = memcg_id; + memcg->kmemcg_id = memcg->id.id - MEM_CGROUP_ID_DIFF; return 0; } @@ -3562,7 +3541,6 @@ static int memcg_online_kmem(struct mem_cgroup *memcg) static void memcg_offline_kmem(struct mem_cgroup *memcg) { struct mem_cgroup *parent; - int kmemcg_id; if (cgroup_memory_nokmem) return; @@ -3577,20 +3555,12 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg) memcg_reparent_objcgs(memcg, parent); /* - * memcg_reparent_list_lrus() can change memcg->kmemcg_id. - * Cache it to local @kmemcg_id. - */ - kmemcg_id = memcg->kmemcg_id; - - /* * After we have finished memcg_reparent_objcgs(), all list_lrus * corresponding to this cgroup are guaranteed to remain empty. * The ordering is imposed by list_lru_node->lock taken by * memcg_reparent_list_lrus(). */ memcg_reparent_list_lrus(memcg, parent); - - ida_free(&memcg_cache_ida, kmemcg_id); } #else static int memcg_online_kmem(struct mem_cgroup *memcg) @@ -5043,7 +5013,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void) return ERR_PTR(error); memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL, - 1, MEM_CGROUP_ID_MAX, + MEM_CGROUP_ID_MIN, MEM_CGROUP_ID_MAX, GFP_KERNEL); if (memcg->id.id < 0) { error = memcg->id.id; @@ -5071,7 +5041,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void) spin_lock_init(&memcg->event_list_lock); memcg->socket_pressure = jiffies; #ifdef CONFIG_MEMCG_KMEM - memcg->kmemcg_id = -1; + memcg->kmemcg_id = MEM_CGROUP_KMEM_ID_MIN; INIT_LIST_HEAD(&memcg->objcg_list); #endif #ifdef CONFIG_CGROUP_WRITEBACK
There are two idrs being used by memory cgroup, one is for kmem ID, another is for memory cgroup ID. The maximum ID of both is 64Ki. Both of them can limit the total number of memory cgroups. Actually, we can reuse memory cgroup ID for kmem ID to simplify the code. Signed-off-by: Muchun Song <songmuchun@bytedance.com> --- include/linux/memcontrol.h | 1 + mm/memcontrol.c | 46 ++++++++-------------------------------------- 2 files changed, 9 insertions(+), 38 deletions(-)