From: Pekka Enberg <penberg@gmail.com>
To: Xunlei Pang <xlpang@linux.alibaba.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Christoph Lameter <cl@linux.com>,
Wen Yang <wenyang@linux.alibaba.com>,
Roman Gushchin <guro@fb.com>,
Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
David Rientjes <rientjes@google.com>,
LKML <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH v2 0/3] mm/slub: Fix count_partial() problem
Date: Thu, 20 Aug 2020 17:02:10 +0300 [thread overview]
Message-ID: <CAOJsxLE9SkLY5V=D=Ot1oyLkbAORagfozYqxk1iNDW6b7QZrwg@mail.gmail.com> (raw)
In-Reply-To: <1597061872-58724-1-git-send-email-xlpang@linux.alibaba.com>
On Mon, Aug 10, 2020 at 3:18 PM Xunlei Pang <xlpang@linux.alibaba.com> wrote:
>
> v1->v2:
> - Improved changelog and variable naming for PATCH 1~2.
> - PATCH3 adds per-cpu counter to avoid performance regression
> in concurrent __slab_free().
>
> [Testing]
> On my 32-cpu 2-socket physical machine:
> Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz
> perf stat --null --repeat 10 -- hackbench 20 thread 20000
>
> == original, no patched
> 19.211637055 seconds time elapsed ( +- 0.57% )
>
> == patched with patch1~2
> Performance counter stats for 'hackbench 20 thread 20000' (10 runs):
>
> 21.731833146 seconds time elapsed ( +- 0.17% )
>
> == patched with patch1~3
> Performance counter stats for 'hackbench 20 thread 20000' (10 runs):
>
> 19.112106847 seconds time elapsed ( +- 0.64% )
>
>
> Xunlei Pang (3):
> mm/slub: Introduce two counters for partial objects
> mm/slub: Get rid of count_partial()
> mm/slub: Use percpu partial free counter
>
> mm/slab.h | 2 +
> mm/slub.c | 124 +++++++++++++++++++++++++++++++++++++++++++-------------------
> 2 files changed, 89 insertions(+), 37 deletions(-)
We probably need to wrap the counters under CONFIG_SLUB_DEBUG because
AFAICT all the code that uses them is also wrapped under it.
An alternative approach for this patch would be to somehow make the
lock in count_partial() more granular, but I don't know how feasible
that actually is.
Anyway, I am OK with this approach:
Reviewed-by: Pekka Enberg <penberg@kernel.org>
You still need to convince Christoph, though, because he had
objections over this approach.
- Pekka
next prev parent reply other threads:[~2020-08-20 14:02 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-10 12:17 [PATCH v2 0/3] mm/slub: Fix count_partial() problem Xunlei Pang
2020-08-10 12:17 ` [PATCH v2 1/3] mm/slub: Introduce two counters for partial objects Xunlei Pang
2020-08-10 12:17 ` [PATCH v2 2/3] mm/slub: Get rid of count_partial() Xunlei Pang
2020-08-10 12:17 ` [PATCH v2 3/3] mm/slub: Use percpu partial free counter Xunlei Pang
2021-03-02 5:56 ` Shu Ming
2021-03-02 9:14 ` Christoph Lameter
2021-03-03 13:46 ` Xunlei Pang
2021-03-03 14:26 ` Matthew Wilcox
2021-03-03 19:15 ` Christoph Lameter
2021-03-03 19:30 ` Matthew Wilcox
2021-03-03 19:55 ` Christoph Lameter
2021-03-03 20:16 ` Matthew Wilcox
2020-08-20 14:02 ` Pekka Enberg [this message]
2020-08-24 10:04 ` [PATCH v2 0/3] mm/slub: Fix count_partial() problem xunlei
2021-03-01 10:31 ` Shu Ming
2021-03-03 13:34 ` Xunlei Pang
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