From: Andi Kleen <andi@firstfloor.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>,
cl@linux-foundation.org, akpm@linux-foundation.org,
rientjes@google.com, hughd@google.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kamezawa.hiroyu@jp.fujitsu.com, kosaki.motohiro@jp.fujitsu.com,
yinghan@google.com
Subject: Re: [GIT PULL] Lockless SLUB slowpaths for v3.1-rc1
Date: Sun, 31 Jul 2011 10:39:58 -0700 [thread overview]
Message-ID: <m2livez6vl.fsf@firstfloor.org> (raw)
In-Reply-To: <CA+55aFw9V-VM5TBwqdKiP0E_g8urth+08nX-_inZ8N1_gFQF4w@mail.gmail.com> (Linus Torvalds's message of "Sat, 30 Jul 2011 08:32:10 -1000")
Linus Torvalds <torvalds@linux-foundation.org> writes:
> On Sat, Jul 30, 2011 at 8:27 AM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> Do we allocate the page map array sufficiently aligned that we
>> actually don't ever have the case of straddling a cacheline? I didn't
>> check.
>
> Oh, and another thing worth checking: did somebody actually check the
> timings for:
I would like to see a followon patch that moves the mem_cgroup
pointer back into struct page. Copying some mem_cgroup people.
>
> - *just* the alignment change?
>
> IOW, maybe some of the netperf improvement isn't from the lockless
> path, but exactly from 'struct page' always being in a single
> cacheline?
>
> - check performance with cmpxchg16b *without* the alignment.
>
> Sometimes especially intel is so good at unaligned accesses that
> you wouldn't see an issue. Now, locked ops are usually special (and
As Eric pointed out CMPXCHG16B requires alignment, it #GPs otherwise.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <andi@firstfloor.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>,
cl@linux-foundation.org, akpm@linux-foundation.org,
rientjes@google.com, hughd@google.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kamezawa.hiroyu@jp.fujitsu.com, kosaki.motohiro@jp.fujitsu.com,
yinghan@google.com
Subject: Re: [GIT PULL] Lockless SLUB slowpaths for v3.1-rc1
Date: Sun, 31 Jul 2011 10:39:58 -0700 [thread overview]
Message-ID: <m2livez6vl.fsf@firstfloor.org> (raw)
In-Reply-To: <CA+55aFw9V-VM5TBwqdKiP0E_g8urth+08nX-_inZ8N1_gFQF4w@mail.gmail.com> (Linus Torvalds's message of "Sat, 30 Jul 2011 08:32:10 -1000")
Linus Torvalds <torvalds@linux-foundation.org> writes:
> On Sat, Jul 30, 2011 at 8:27 AM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> Do we allocate the page map array sufficiently aligned that we
>> actually don't ever have the case of straddling a cacheline? I didn't
>> check.
>
> Oh, and another thing worth checking: did somebody actually check the
> timings for:
I would like to see a followon patch that moves the mem_cgroup
pointer back into struct page. Copying some mem_cgroup people.
>
> - *just* the alignment change?
>
> IOW, maybe some of the netperf improvement isn't from the lockless
> path, but exactly from 'struct page' always being in a single
> cacheline?
>
> - check performance with cmpxchg16b *without* the alignment.
>
> Sometimes especially intel is so good at unaligned accesses that
> you wouldn't see an issue. Now, locked ops are usually special (and
As Eric pointed out CMPXCHG16B requires alignment, it #GPs otherwise.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
--
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next prev parent reply other threads:[~2011-07-31 17:40 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-28 22:47 [GIT PULL] Lockless SLUB slowpaths for v3.1-rc1 Pekka Enberg
2011-07-28 22:47 ` Pekka Enberg
2011-07-29 15:04 ` Christoph Lameter
2011-07-29 15:04 ` Christoph Lameter
2011-07-29 23:18 ` Andi Kleen
2011-07-29 23:18 ` Andi Kleen
2011-07-30 6:33 ` Eric Dumazet
2011-07-30 6:33 ` Eric Dumazet
2011-07-31 18:50 ` David Rientjes
2011-07-31 18:50 ` David Rientjes
2011-07-31 20:24 ` David Rientjes
2011-07-31 20:24 ` David Rientjes
2011-07-31 20:45 ` Pekka Enberg
2011-07-31 20:45 ` Pekka Enberg
2011-07-31 21:55 ` David Rientjes
2011-07-31 21:55 ` David Rientjes
2011-08-01 5:08 ` Pekka Enberg
2011-08-01 5:08 ` Pekka Enberg
2011-08-01 10:02 ` David Rientjes
2011-08-01 10:02 ` David Rientjes
2011-08-01 12:45 ` Pekka Enberg
2011-08-01 12:45 ` Pekka Enberg
2011-08-02 2:43 ` David Rientjes
2011-08-02 2:43 ` David Rientjes
2011-08-01 12:06 ` Pekka Enberg
2011-08-01 12:06 ` Pekka Enberg
2011-08-01 15:55 ` Christoph Lameter
2011-08-01 15:55 ` Christoph Lameter
2011-08-02 4:05 ` David Rientjes
2011-08-02 4:05 ` David Rientjes
2011-08-02 14:15 ` Christoph Lameter
2011-08-02 14:15 ` Christoph Lameter
2011-08-02 16:24 ` David Rientjes
2011-08-02 16:24 ` David Rientjes
2011-08-02 16:36 ` Christoph Lameter
2011-08-02 16:36 ` Christoph Lameter
2011-08-02 20:02 ` David Rientjes
2011-08-02 20:02 ` David Rientjes
2011-08-03 14:09 ` Christoph Lameter
2011-08-03 14:09 ` Christoph Lameter
2011-08-08 20:04 ` David Rientjes
2011-08-08 20:04 ` David Rientjes
2011-07-30 18:27 ` Linus Torvalds
2011-07-30 18:27 ` Linus Torvalds
2011-07-30 18:32 ` Linus Torvalds
2011-07-30 18:32 ` Linus Torvalds
2011-07-31 17:39 ` Andi Kleen [this message]
2011-07-31 17:39 ` Andi Kleen
2011-08-01 0:22 ` KAMEZAWA Hiroyuki
2011-08-01 0:22 ` KAMEZAWA Hiroyuki
2011-07-31 18:11 ` David Rientjes
2011-07-31 18:11 ` David Rientjes
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