diff options
| author | Roman Gushchin <guro@fb.com> | 2021-02-24 23:03:11 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-25 00:38:29 +0300 |
| commit | 2e9bd483159939ed2c0704b914294653c8341d25 (patch) | |
| tree | 878ce98090f4ad550e476a5e80c746f62c44fda8 /mm/slub.c | |
| parent | cad8320b4b395702e49578580c70026c8271ea88 (diff) | |
| download | linux-2e9bd483159939ed2c0704b914294653c8341d25.tar.xz | |
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 'mm/slub.c')
| -rw-r--r-- | mm/slub.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/slub.c b/mm/slub.c index e0fef8f8d4bf..ca566361561e 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1785,7 +1785,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) page->objects = oo_objects(oo); - account_slab_page(page, oo_order(oo), s); + account_slab_page(page, oo_order(oo), s, flags); page->slab_cache = s; __SetPageSlab(page); |