From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Christoph Lameter <cl@linux.com>
Cc: linux-mm@kvack.org, Vladimir Davydov <vdavydov@virtuozzo.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
brouer@redhat.com
Subject: Re: [RFC PATCH 2/2] slab: implement bulk free in SLAB allocator
Date: Mon, 7 Dec 2015 12:25:49 +0100 [thread overview]
Message-ID: <20151207122549.109e82db@redhat.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1512041111180.21819@east.gentwo.org>
On Fri, 4 Dec 2015 11:17:02 -0600 (CST)
Christoph Lameter <cl@linux.com> wrote:
> On Thu, 3 Dec 2015, Jesper Dangaard Brouer wrote:
>
> > +void kmem_cache_free_bulk(struct kmem_cache *orig_s, size_t size, void **p)
>
> orig_s? Thats strange
>
> > +{
> > + struct kmem_cache *s;
>
> s?
The "s" comes from the slub.c code uses "struct kmem_cache *s" everywhere.
> > + size_t i;
> > +
> > + local_irq_disable();
> > + for (i = 0; i < size; i++) {
> > + void *objp = p[i];
> > +
> > + s = cache_from_obj(orig_s, objp);
>
> Does this support freeing objects from a set of different caches?
This is for supporting memcg (CONFIG_MEMCG_KMEM).
Quoting from commit 033745189b1b ("slub: add missing kmem cgroup
support to kmem_cache_free_bulk"):
Incoming bulk free objects can belong to different kmem cgroups, and
object free call can happen at a later point outside memcg context. Thus,
we need to keep the orig kmem_cache, to correctly verify if a memcg object
match against its "root_cache" (s->memcg_params.root_cache).
> > +
> > + debug_check_no_locks_freed(objp, s->object_size);
> > + if (!(s->flags & SLAB_DEBUG_OBJECTS))
> > + debug_check_no_obj_freed(objp, s->object_size);
> > +
> > + __cache_free(s, objp, _RET_IP_);
>
> The function could be further optimized if you take the code from
> __cache_free() and move stuff outside of the loop. The alien cache check
> f.e. and the Pfmemalloc checking may be moved out. The call to
> virt_to_head page may also be avoided if the objects are on the same
> page as the last. So you may be able to function calls for the
> fastpath in the inner loop which may accelerate frees significantly.
Interesting! Maybe we can do a followup patch to pullout last
optimization's. Right now I'm mostly interested in correctness and
clean code. And we are already looking at a 80% speedup with these
patches ;-)
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer
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next prev parent reply other threads:[~2015-12-07 11:25 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-03 15:56 [RFC PATCH 0/2] slab: implement bulking for SLAB allocator Jesper Dangaard Brouer
2015-12-03 15:57 ` [RFC PATCH 1/2] slab: implement bulk alloc in " Jesper Dangaard Brouer
2015-12-04 10:16 ` Jesper Dangaard Brouer
2015-12-04 17:10 ` Christoph Lameter
2015-12-07 10:20 ` Jesper Dangaard Brouer
2015-12-07 14:57 ` Christoph Lameter
2015-12-03 15:57 ` [RFC PATCH 2/2] slab: implement bulk free " Jesper Dangaard Brouer
2015-12-04 17:17 ` Christoph Lameter
2015-12-07 11:25 ` Jesper Dangaard Brouer [this message]
2015-12-07 14:59 ` Christoph Lameter
2015-12-08 13:39 ` Jesper Dangaard Brouer
2015-12-08 14:11 ` Christoph Lameter
2015-12-08 14:12 ` Vladimir Davydov
2015-12-08 14:15 ` Christoph Lameter
2015-12-08 14:56 ` Vladimir Davydov
2015-12-08 15:13 ` Jesper Dangaard Brouer
2015-12-08 15:32 ` Christoph Lameter
2015-12-04 9:01 ` [RFC PATCH 0/2] slab: implement bulking for " Jesper Dangaard Brouer
2015-12-08 16:18 ` [RFC PATCH V2 0/9] slab: cleanup and bulk API for SLAB Jesper Dangaard Brouer
2015-12-08 16:18 ` [RFC PATCH V2 1/9] mm/slab: move SLUB alloc hooks to common mm/slab.h Jesper Dangaard Brouer
2015-12-09 15:43 ` Christoph Lameter
2015-12-08 16:18 ` [RFC PATCH V2 2/9] mm: generalize avoid fault-inject on bootstrap kmem_cache Jesper Dangaard Brouer
2015-12-09 2:36 ` Joonsoo Kim
2015-12-08 16:18 ` [RFC PATCH V2 3/9] slab: use slab_pre_alloc_hook in SLAB allocator Jesper Dangaard Brouer
2015-12-08 16:18 ` [RFC PATCH V2 4/9] mm: kmemcheck skip object if slab allocation failed Jesper Dangaard Brouer
2015-12-08 16:18 ` [RFC PATCH V2 5/9] slab: use slab_post_alloc_hook in SLAB allocator Jesper Dangaard Brouer
2015-12-08 16:18 ` [RFC PATCH V2 6/9] slab: implement bulk alloc " Jesper Dangaard Brouer
2015-12-08 16:18 ` [RFC PATCH V2 7/9] slab: avoid running debug SLAB code with IRQs disabled for alloc_bulk Jesper Dangaard Brouer
2015-12-08 16:19 ` [RFC PATCH V2 8/9] slab: implement bulk free in SLAB allocator Jesper Dangaard Brouer
2015-12-09 16:06 ` Christoph Lameter
2015-12-09 18:53 ` Jesper Dangaard Brouer
2015-12-09 19:41 ` Christoph Lameter
2015-12-09 20:50 ` Jesper Dangaard Brouer
2015-12-10 15:15 ` Christoph Lameter
2015-12-10 15:10 ` Jesper Dangaard Brouer
2015-12-10 15:18 ` Christoph Lameter
2015-12-10 15:26 ` Vladimir Davydov
2015-12-10 17:24 ` Christoph Lameter
2015-12-14 15:19 ` Jesper Dangaard Brouer
2015-12-15 12:02 ` Jesper Dangaard Brouer
2015-12-08 16:19 ` [RFC PATCH V2 9/9] slab: annotate code to generate more compact asm code Jesper Dangaard Brouer
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