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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Anton Starikov <ant.starikov@gmail.com>,
	Ingo Molnar <mingo@elte.hu>,
	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 12:52:44 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LFD.2.00.1003231242420.18017@i5.linux-foundation.org> (raw)
In-Reply-To: <20100323112141.7f248f2b.akpm@linux-foundation.org>



On Tue, 23 Mar 2010, Andrew Morton wrote:
> 
> You should be able to simply set CONFIG_RWSEM_GENERIC_SPINLOCK=n,
> CONFIG_RWSEM_XCHGADD_ALGORITHM=y by hand, as I mentioned earlier?

No. Doesn't work. The XADD code simply never worked on x86-64, which is 
why those three commits I pointed at are required.

Oh, and you need one more commit (at least) in addition to the three I 
already mentioned - the one that actually adds the x86-64 wrappers and 
Kconfig option:

	bafaecd x86-64: support native xadd rwsem implementation

so the minimal list of commits (on top of 2.6.33) is at least

	59c33fa x86-32: clean up rwsem inline asm statements
	5d0b723 x86: clean up rwsem type system
	bafaecd x86-64: support native xadd rwsem implementation
	1838ef1 x86-64, rwsem: 64-bit xadd rwsem implementation

and I just verified that they at least cherry-pick cleanly (in that 
order). I _think_ it would be good to also do

	0d1622d x86-64, rwsem: Avoid store forwarding hazard in __downgrade_write

but that one is a small detail, not anything fundamentally important.

			Linus

WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Anton Starikov <ant.starikov@gmail.com>,
	Ingo Molnar <mingo@elte.hu>,
	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 12:52:44 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LFD.2.00.1003231242420.18017@i5.linux-foundation.org> (raw)
In-Reply-To: <20100323112141.7f248f2b.akpm@linux-foundation.org>



On Tue, 23 Mar 2010, Andrew Morton wrote:
> 
> You should be able to simply set CONFIG_RWSEM_GENERIC_SPINLOCK=n,
> CONFIG_RWSEM_XCHGADD_ALGORITHM=y by hand, as I mentioned earlier?

No. Doesn't work. The XADD code simply never worked on x86-64, which is 
why those three commits I pointed at are required.

Oh, and you need one more commit (at least) in addition to the three I 
already mentioned - the one that actually adds the x86-64 wrappers and 
Kconfig option:

	bafaecd x86-64: support native xadd rwsem implementation

so the minimal list of commits (on top of 2.6.33) is at least

	59c33fa x86-32: clean up rwsem inline asm statements
	5d0b723 x86: clean up rwsem type system
	bafaecd x86-64: support native xadd rwsem implementation
	1838ef1 x86-64, rwsem: 64-bit xadd rwsem implementation

and I just verified that they at least cherry-pick cleanly (in that 
order). I _think_ it would be good to also do

	0d1622d x86-64, rwsem: Avoid store forwarding hazard in __downgrade_write

but that one is a small detail, not anything fundamentally important.

			Linus

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  parent reply	other threads:[~2010-03-23 19:58 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
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 [this message]
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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