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authorRoman Gushchin <guro@fb.com>2021-02-24 12:03:11 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-24 13:38:29 -0800
commit2e9bd483159939ed2c0704b914294653c8341d25 (patch)
tree878ce98090f4ad550e476a5e80c746f62c44fda8 /include
parentcad8320b4b395702e49578580c70026c8271ea88 (diff)
mm: memcg/slab: pre-allocate obj_cgroups for slab caches with SLAB_ACCOUNT
In general it's unknown in advance if a slab page will contain accounted objects or not. In order to avoid memory waste, an obj_cgroup vector is allocated dynamically when a need to account of a new object arises. Such approach is memory efficient, but requires an expensive cmpxchg() to set up the memcg/objcgs pointer, because an allocation can race with a different allocation on another cpu. But in some common cases it's known for sure that a slab page will contain accounted objects: if the page belongs to a slab cache with a SLAB_ACCOUNT flag set. It includes such popular objects like vm_area_struct, anon_vma, task_struct, etc. In such cases we can pre-allocate the objcgs vector and simple assign it to the page without any atomic operations, because at this early stage the page is not visible to anyone else. A very simplistic benchmark (allocating 10000000 64-bytes objects in a row) shows ~15% win. In the real life it seems that most workloads are not very sensitive to the speed of (accounted) slab allocations. [guro@fb.com: open-code set_page_objcgs() and add some comments, by Johannes] Link: https://lkml.kernel.org/r/20201113001926.GA2934489@carbon.dhcp.thefacebook.com [akpm@linux-foundation.org: fix it for mm-slub-call-account_slab_page-after-slab-page-initialization-fix.patch] Link: https://lkml.kernel.org/r/20201110195753.530157-2-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/memcontrol.h19
1 files changed, 0 insertions, 19 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index eeb0b52203e9..7a4dd1cb19fe 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -475,19 +475,6 @@ static inline struct obj_cgroup **page_objcgs_check(struct page *page)
return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
}
-/*
- * set_page_objcgs - associate a page with a object cgroups vector
- * @page: a pointer to the page struct
- * @objcgs: a pointer to the object cgroups vector
- *
- * Atomically associates a page with a vector of object cgroups.
- */
-static inline bool set_page_objcgs(struct page *page,
- struct obj_cgroup **objcgs)
-{
- return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs |
- MEMCG_DATA_OBJCGS);
-}
#else
static inline struct obj_cgroup **page_objcgs(struct page *page)
{
@@ -498,12 +485,6 @@ static inline struct obj_cgroup **page_objcgs_check(struct page *page)
{
return NULL;
}
-
-static inline bool set_page_objcgs(struct page *page,
- struct obj_cgroup **objcgs)
-{
- return true;
-}
#endif
static __always_inline bool memcg_stat_item_in_bytes(int idx)