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From: Anton Starikov <ant.starikov@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	bugzilla-daemon@bugzilla.kernel.org,
	bugme-daemon@bugzilla.kernel.org,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [Bugme-new] [Bug 15618] New: 2.6.18->2.6.32->2.6.33 huge regression in performance
Date: Tue, 23 Mar 2010 18:57:34 +0100	[thread overview]
Message-ID: <54F3A3FB-E99F-4278-AAAB-5B6A09247C4B@gmail.com> (raw)
In-Reply-To: <alpine.LFD.2.00.1003231037410.18017@i5.linux-foundation.org>


On Mar 23, 2010, at 6:45 PM, Linus Torvalds wrote:

> 
> 
> On Tue, 23 Mar 2010, Ingo Molnar wrote:
>> 
>> It shows a very brutal amount of page fault invoked mmap_sem spinning 
>> overhead.
> 
> Isn't this already fixed? It's the same old "x86-64 rwsemaphores are using 
> the shit-for-brains generic version" thing, and it's fixed by
> 
> 	1838ef1 x86-64, rwsem: 64-bit xadd rwsem implementation
> 	5d0b723 x86: clean up rwsem type system
> 	59c33fa x86-32: clean up rwsem inline asm statements
> 
> NOTE! None of those are in 2.6.33 - they were merged afterwards. But they 
> are in 2.6.34-rc1 (and obviously current -git). So Anton would have to 
> compile his own kernel to test his load.

Thanks for info, I will try it now.

> We could mark them as stable material if the load in question is a real 
> load rather than just a test-case. On one of the random page-fault 
> benchmarks the rwsem fix was something like a 400% performance 
> improvement, and it was apparently visible in real life on some crazy SGI 
> "initialize huge heap concurrently on lots of threads" load.

It is not just a test-case, it is real-life code. With real-life problems on 2.6.32 and later :)


Anton.

WARNING: multiple messages have this Message-ID (diff)
From: Anton Starikov <ant.starikov@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	bugzilla-daemon@bugzilla.kernel.org,
	bugme-daemon@bugzilla.kernel.org,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [Bugme-new] [Bug 15618] New: 2.6.18->2.6.32->2.6.33 huge regression in performance
Date: Tue, 23 Mar 2010 18:57:34 +0100	[thread overview]
Message-ID: <54F3A3FB-E99F-4278-AAAB-5B6A09247C4B@gmail.com> (raw)
In-Reply-To: <alpine.LFD.2.00.1003231037410.18017@i5.linux-foundation.org>


On Mar 23, 2010, at 6:45 PM, Linus Torvalds wrote:

> 
> 
> On Tue, 23 Mar 2010, Ingo Molnar wrote:
>> 
>> It shows a very brutal amount of page fault invoked mmap_sem spinning 
>> overhead.
> 
> Isn't this already fixed? It's the same old "x86-64 rwsemaphores are using 
> the shit-for-brains generic version" thing, and it's fixed by
> 
> 	1838ef1 x86-64, rwsem: 64-bit xadd rwsem implementation
> 	5d0b723 x86: clean up rwsem type system
> 	59c33fa x86-32: clean up rwsem inline asm statements
> 
> NOTE! None of those are in 2.6.33 - they were merged afterwards. But they 
> are in 2.6.34-rc1 (and obviously current -git). So Anton would have to 
> compile his own kernel to test his load.

Thanks for info, I will try it now.

> We could mark them as stable material if the load in question is a real 
> load rather than just a test-case. On one of the random page-fault 
> benchmarks the rwsem fix was something like a 400% performance 
> improvement, and it was apparently visible in real life on some crazy SGI 
> "initialize huge heap concurrently on lots of threads" load.

It is not just a test-case, it is real-life code. With real-life problems on 2.6.32 and later :)


Anton.
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  reply	other threads:[~2010-03-23 17:57 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-15618-10286@https.bugzilla.kernel.org/>
2010-03-23 14:22 ` [Bugme-new] [Bug 15618] New: 2.6.18->2.6.32->2.6.33 huge regression in performance Andrew Morton
2010-03-23 14:22   ` Andrew Morton
2010-03-23 17:34   ` Ingo Molnar
2010-03-23 17:34     ` Ingo Molnar
2010-03-23 17:45     ` Linus Torvalds
2010-03-23 17:45       ` Linus Torvalds
2010-03-23 17:57       ` Anton Starikov [this message]
2010-03-23 17:57         ` Anton Starikov
2010-03-23 18:00       ` Ingo Molnar
2010-03-23 18:00         ` Ingo Molnar
2010-03-23 18:03         ` Anton Starikov
2010-03-23 18:03           ` Anton Starikov
2010-03-23 18:21           ` Andrew Morton
2010-03-23 18:21             ` Andrew Morton
2010-03-23 18:25             ` Anton Starikov
2010-03-23 18:25               ` Anton Starikov
2010-03-23 19:22               ` Robin Holt
2010-03-23 19:22                 ` Robin Holt
2010-03-23 19:30                 ` Anton Starikov
2010-03-23 19:30                   ` Anton Starikov
2010-03-23 19:49                   ` Robin Holt
2010-03-23 19:49                     ` Robin Holt
2010-03-23 19:57                     ` Robin Holt
2010-03-23 19:57                       ` Robin Holt
2010-03-23 19:50                 ` Anton Starikov
2010-03-23 19:50                   ` Anton Starikov
2010-03-23 19:52             ` Linus Torvalds
2010-03-23 19:52               ` Linus Torvalds
2010-03-24 16:40           ` Roland Dreier
2010-03-24 16:40             ` Roland Dreier
2010-03-26  3:24             ` Anton Starikov
2010-03-26  3:24               ` Anton Starikov
2010-03-23 19:14       ` Anton Starikov
2010-03-23 19:14         ` Anton Starikov
2010-03-23 19:17         ` Peter Zijlstra
2010-03-23 19:17           ` Peter Zijlstra
2010-03-23 19:42           ` Anton Starikov
2010-03-23 19:54         ` Linus Torvalds
2010-03-23 19:54           ` Linus Torvalds
2010-03-23 20:43           ` Anton Starikov
2010-03-23 20:43             ` Anton Starikov
2010-03-23 23:04             ` Linus Torvalds
2010-03-23 23:04               ` Linus Torvalds
2010-03-23 23:19               ` Anton Starikov
2010-03-23 23:19                 ` Anton Starikov
2010-03-23 23:36               ` Ingo Molnar
2010-03-23 23:36                 ` Ingo Molnar
2010-03-23 23:55                 ` Linus Torvalds
2010-03-23 23:55                   ` Linus Torvalds
2010-03-24  0:03                   ` Anton Starikov
2010-03-24  0:03                     ` Anton Starikov
2010-03-24  2:15                   ` Andi Kleen
2010-03-24  2:15                     ` Andi Kleen
2010-03-24  3:00                     ` Linus Torvalds
2010-03-24  3:00                       ` Linus Torvalds
2010-04-19 18:19                       ` Greg KH
2010-04-19 18:19                         ` Greg KH
2010-03-23 18:13     ` Andrew Morton
2010-03-23 18:13       ` Andrew Morton
2010-03-23 18:19       ` Anton Starikov
2010-03-23 18:19         ` Anton Starikov
2010-03-23 18:27       ` Ingo Molnar
2010-03-23 18:27         ` Ingo Molnar
2010-03-23 21:19       ` Anton Starikov
2010-03-23 21:19         ` Anton Starikov
2010-04-02 18:57   ` Lee Schermerhorn

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