From: Roman Gushchin <guro@fb.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>, <linux-mm@kvack.org>,
<kernel-team@fb.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 07/19] mm: memcg/slab: allocate obj_cgroups for non-root slab pages
Date: Fri, 22 May 2020 18:32:00 -0700 [thread overview]
Message-ID: <20200523013200.GA356168@carbon.DHCP.thefacebook.com> (raw)
In-Reply-To: <930fb5f4-0666-5db0-0fcf-a78171bf29be@suse.cz>
On Fri, May 22, 2020 at 08:27:15PM +0200, Vlastimil Babka wrote:
> On 4/22/20 10:46 PM, Roman Gushchin wrote:
> > Allocate and release memory to store obj_cgroup pointers for each
> > non-root slab page. Reuse page->mem_cgroup pointer to store a pointer
> > to the allocated space.
> >
> > To distinguish between obj_cgroups and memcg pointers in case
> > when it's not obvious which one is used (as in page_cgroup_ino()),
> > let's always set the lowest bit in the obj_cgroup case.
> >
> > Signed-off-by: Roman Gushchin <guro@fb.com>
>
> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Thank you!
>
> But I have a suggestion:
>
> ...
>
> > --- a/include/linux/slub_def.h
> > +++ b/include/linux/slub_def.h
> > @@ -191,4 +191,6 @@ static inline unsigned int obj_to_index(const struct kmem_cache *cache,
> > cache->reciprocal_size);
> > }
> >
> > +extern int objs_per_slab(struct kmem_cache *cache);
> > +
> > #endif /* _LINUX_SLUB_DEF_H */
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 7f87a0eeafec..63826e460b3f 100644
>
> ...
>
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -5992,4 +5992,9 @@ ssize_t slabinfo_write(struct file *file, const char __user *buffer,
> > {
> > return -EIO;
> > }
> > +
> > +int objs_per_slab(struct kmem_cache *cache)
> > +{
> > + return oo_objects(cache->oo);
> > +}
> > #endif /* CONFIG_SLUB_DEBUG */
> >
>
> It's somewhat unfortunate to function call just for this. Although perhaps
> compiler can be smart enough as charge_slab_page() (that callse objs_per_slab())
> is inline and called from alloc_slab_page() which is also in mm/slub.c.
>
> But it might be also a bit wasteful in case SLUB doesn't manage to allocate its
> desired order, but smaller. The actual number of objects is then in page->objects.
>
> So ideally this should use something like objs_per_slab_page(cache, page) where
> SLAB supplies cache->num and SLUB page->objects, both implementations inline,
> and ignoring the other parameter?
Yeah, good point, makes total sense to me. I'll implement it in the next version
of the patchset.
Thank you!
next prev parent reply other threads:[~2020-05-23 1:32 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 20:46 [PATCH v3 00/19] The new cgroup slab memory controller Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 01/19] mm: memcg: factor out memcg- and lruvec-level changes out of __mod_lruvec_state() Roman Gushchin
2020-05-07 20:33 ` Johannes Weiner
2020-05-20 10:49 ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 02/19] mm: memcg: prepare for byte-sized vmstat items Roman Gushchin
2020-05-07 20:34 ` Johannes Weiner
2020-05-20 11:31 ` Vlastimil Babka
2020-05-20 11:36 ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 03/19] mm: memcg: convert vmstat slab counters to bytes Roman Gushchin
2020-05-07 20:41 ` Johannes Weiner
2020-05-20 12:25 ` Vlastimil Babka
2020-05-20 19:26 ` Roman Gushchin
2020-05-21 9:57 ` Vlastimil Babka
2020-05-21 21:14 ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 04/19] mm: slub: implement SLUB version of obj_to_index() Roman Gushchin
2020-04-22 23:52 ` Christopher Lameter
2020-04-23 0:05 ` Roman Gushchin
2020-04-25 2:10 ` Christopher Lameter
2020-04-25 2:46 ` Roman Gushchin
2020-04-27 16:21 ` Christopher Lameter
2020-04-27 16:46 ` Roman Gushchin
2020-04-28 17:06 ` Roman Gushchin
2020-04-28 17:45 ` Johannes Weiner
2020-04-30 16:29 ` Christopher Lameter
2020-04-30 17:15 ` Roman Gushchin
2020-05-02 23:54 ` Christopher Lameter
2020-05-04 18:29 ` Roman Gushchin
2020-05-08 21:35 ` Christopher Lameter
2020-05-13 0:57 ` Roman Gushchin
2020-05-15 21:45 ` Christopher Lameter
2020-05-15 22:12 ` Roman Gushchin
2020-05-20 9:51 ` Vlastimil Babka
2020-05-20 20:57 ` Roman Gushchin
2020-05-15 20:02 ` Roman Gushchin
2020-04-23 21:01 ` Roman Gushchin
2020-04-25 2:10 ` Christopher Lameter
2020-05-20 13:51 ` Vlastimil Babka
2020-05-20 21:00 ` Roman Gushchin
2020-05-21 11:01 ` Vlastimil Babka
2020-05-21 21:06 ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 05/19] mm: memcontrol: decouple reference counting from page accounting Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 06/19] mm: memcg/slab: obj_cgroup API Roman Gushchin
2020-05-07 21:03 ` Johannes Weiner
2020-05-07 22:26 ` Roman Gushchin
2020-05-12 22:56 ` Johannes Weiner
2020-05-15 22:01 ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 07/19] mm: memcg/slab: allocate obj_cgroups for non-root slab pages Roman Gushchin
2020-04-23 20:20 ` Roman Gushchin
2020-05-22 18:27 ` Vlastimil Babka
2020-05-23 1:32 ` Roman Gushchin [this message]
2020-05-26 17:50 ` Roman Gushchin
2020-05-25 14:46 ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 08/19] mm: memcg/slab: save obj_cgroup for non-root slab objects Roman Gushchin
2020-05-25 15:07 ` Vlastimil Babka
2020-05-26 17:53 ` Roman Gushchin
2020-05-27 11:03 ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 09/19] mm: memcg/slab: charge individual slab objects instead of pages Roman Gushchin
2020-05-25 16:10 ` Vlastimil Babka
2020-05-26 18:04 ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 10/19] mm: memcg/slab: deprecate memory.kmem.slabinfo Roman Gushchin
2020-05-07 21:05 ` Johannes Weiner
2020-04-22 20:47 ` [PATCH v3 11/19] mm: memcg/slab: move memcg_kmem_bypass() to memcontrol.h Roman Gushchin
2020-05-25 17:03 ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 12/19] mm: memcg/slab: use a single set of kmem_caches for all accounted allocations Roman Gushchin
2020-05-26 10:12 ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 13/19] mm: memcg/slab: simplify memcg cache creation Roman Gushchin
2020-05-26 10:31 ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 14/19] mm: memcg/slab: deprecate memcg_kmem_get_cache() Roman Gushchin
2020-05-26 10:34 ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 15/19] mm: memcg/slab: deprecate slab_root_caches Roman Gushchin
2020-05-26 10:52 ` Vlastimil Babka
2020-05-26 18:50 ` Roman Gushchin
2020-04-22 20:47 ` [PATCH v3 16/19] mm: memcg/slab: remove redundant check in memcg_accumulate_slabinfo() Roman Gushchin
2020-05-26 11:31 ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 17/19] mm: memcg/slab: use a single set of kmem_caches for all allocations Roman Gushchin
2020-05-26 14:55 ` Vlastimil Babka
2020-05-27 8:35 ` Jesper Dangaard Brouer
2020-04-22 20:47 ` [PATCH v3 18/19] kselftests: cgroup: add kernel memory accounting tests Roman Gushchin
2020-05-26 15:24 ` Vlastimil Babka
2020-05-26 15:45 ` Roman Gushchin
2020-05-27 17:00 ` Vlastimil Babka
2020-05-27 20:45 ` Roman Gushchin
2020-04-22 20:47 ` [PATCH v3 19/19] tools/cgroup: add memcg_slabinfo.py tool Roman Gushchin
2020-05-05 15:59 ` Tejun Heo
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