From: Jeremy Fitzhardinge <jeremy@goop.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@elte.hu>,
the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Nick Piggin <npiggin@kernel.dk>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Subject: Re: [PATCH 00/18] x86: Ticket lock + cmpxchg cleanup
Date: Wed, 24 Aug 2011 16:10:21 -0700 [thread overview]
Message-ID: <4E5584DD.6000907@goop.org> (raw)
In-Reply-To: <4E5583B3.8080309@zytor.com>
On 08/24/2011 04:05 PM, H. Peter Anvin wrote:
> On 08/24/2011 03:59 PM, Jeremy Fitzhardinge wrote:
>> On 08/24/2011 03:53 PM, Linus Torvalds wrote:
>>> On Wed, Aug 24, 2011 at 1:10 PM, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
>>>> Could we just kill SMP support for OOSTORE machines now? That would be
>>>> the cleanest possible fix...
>>> No it wouldn't. The asm version would *still* be cleaner than the "C
>>> plus random barriers".
>>>
>>> It's not like the C version is "portable" in any case.
>> If there's no need to have a locked instruction, then it could simply be:
>>
>> barrier();
>> lock->head++;
>> barrier();
>>
>> with no need for asm at all.
>>
> That's not guaranteed in any way to generate a locally atomic instruction.
Doesn't need to be. The final write needs to be locally atomic, but we
assume that a lot.
J
next prev parent reply other threads:[~2011-08-24 23:10 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-24 17:52 [PATCH 00/18] x86: Ticket lock + cmpxchg cleanup Jeremy Fitzhardinge
2011-08-24 17:52 ` [PATCH 01/18] x86/ticketlock: clean up types and accessors Jeremy Fitzhardinge
2011-08-24 17:52 ` [PATCH 02/18] x86/ticketlock: convert spin loop to C Jeremy Fitzhardinge
2011-08-24 20:02 ` Andi Kleen
2011-08-24 17:52 ` [PATCH 03/18] x86/ticketlock: Use C for __ticket_spin_unlock Jeremy Fitzhardinge
2011-08-24 18:01 ` Linus Torvalds
2011-08-24 17:52 ` [PATCH 04/18] x86/ticketlock: make large and small ticket versions of spin_lock the same Jeremy Fitzhardinge
2011-08-24 17:52 ` [PATCH 05/18] x86/ticketlock: make __ticket_spin_lock common Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 06/18] x86/ticketlock: make __ticket_spin_trylock common Jeremy Fitzhardinge
2011-08-24 20:00 ` Andi Kleen
2011-08-24 21:38 ` Linus Torvalds
2011-08-24 21:43 ` Jeremy Fitzhardinge
2011-08-24 21:43 ` Andi Kleen
2011-08-24 21:48 ` Jeremy Fitzhardinge
2011-08-24 21:53 ` Andi Kleen
2011-08-24 17:53 ` [PATCH 07/18] x86: add xadd helper macro Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 08/18] x86/ticketlock: use xadd helper Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 09/18] x86/cmpxchg: linux/alternative.h has LOCK_PREFIX Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 10/18] x86/cmpxchg: move 32-bit __cmpxchg_wrong_size to match 64 bit Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 11/18] x86/cmpxchg: move 64-bit set64_bit() to match 32-bit Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 12/18] x86/cmpxchg: unify cmpxchg into cmpxchg.h Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 13/18] x86: add cmpxchg_flag() variant Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 14/18] x86/ticketlocks: use cmpxchg_flag for trylock Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 15/18] x86: use cmpxchg_flag() where applicable Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 16/18] x86: report xchg/cmpxchg/xadd usage errors consistently Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 17/18] x86: add local and sync variants of xadd Jeremy Fitzhardinge
2011-08-24 17:53 ` [PATCH 18/18] x86: use xadd helper more widely Jeremy Fitzhardinge
2011-08-24 18:03 ` [PATCH 00/18] x86: Ticket lock + cmpxchg cleanup Peter Zijlstra
2011-08-24 18:24 ` Linus Torvalds
2011-08-24 20:10 ` Jeremy Fitzhardinge
2011-08-24 22:53 ` Linus Torvalds
2011-08-24 22:59 ` Jeremy Fitzhardinge
2011-08-24 23:05 ` H. Peter Anvin
2011-08-24 23:09 ` Linus Torvalds
2011-08-24 23:21 ` Linus Torvalds
2011-08-24 23:30 ` Jeremy Fitzhardinge
2011-08-24 23:10 ` Jeremy Fitzhardinge [this message]
2011-08-24 21:36 ` [PATCH 01/12] x86/cmpxchg: linux/alternative.h has LOCK_PREFIX Jeremy Fitzhardinge
2011-08-24 21:36 ` [PATCH 02/12] x86/cmpxchg: move 32-bit __cmpxchg_wrong_size to match 64 bit Jeremy Fitzhardinge
2011-08-24 21:37 ` [PATCH 03/12] x86/cmpxchg: move 64-bit set64_bit() to match 32-bit Jeremy Fitzhardinge
2011-08-24 21:37 ` [PATCH 04/12] x86/cmpxchg: unify cmpxchg into cmpxchg.h Jeremy Fitzhardinge
2011-08-24 21:37 ` [PATCH 05/12] x86: add xadd helper macro Jeremy Fitzhardinge
2011-08-24 21:37 ` [PATCH 06/12] x86: add cmpxchg_flag() variant Jeremy Fitzhardinge
2011-08-24 21:37 ` [PATCH 07/12] x86: use cmpxchg_flag() where applicable Jeremy Fitzhardinge
2011-08-24 21:56 ` Linus Torvalds
2011-08-24 22:01 ` H. Peter Anvin
2011-08-24 22:03 ` Jeremy Fitzhardinge
2011-08-24 22:05 ` H. Peter Anvin
2011-08-24 22:02 ` Jeremy Fitzhardinge
2011-08-24 21:37 ` [PATCH 08/12] x86: use xadd helper more widely Jeremy Fitzhardinge
2011-08-24 21:37 ` [PATCH 09/12] x86/ticketlock: clean up types and accessors Jeremy Fitzhardinge
2011-08-24 21:37 ` [PATCH 10/12] x86/ticketlock: convert spin loop to C Jeremy Fitzhardinge
2011-08-24 21:37 ` [PATCH 11/12] x86/ticketlock: convert __ticket_spin_lock to use xadd() Jeremy Fitzhardinge
2011-08-24 21:37 ` [PATCH 12/12] x86/ticketlock: make __ticket_spin_trylock common Jeremy Fitzhardinge
2011-08-24 21:46 ` [PATCH 00/18] x86: Ticket lock + cmpxchg cleanup Jeremy Fitzhardinge
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