From: "H. Peter Anvin" <hpa@zytor.com>
To: Christoph Lameter <cl@linux.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
Pekka Enberg <penberg@cs.helsinki.fi>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [slubllv5 07/25] x86: Add support for cmpxchg_double
Date: Wed, 01 Jun 2011 08:41:42 -0700 [thread overview]
Message-ID: <4DE65DB6.4050801@zytor.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1106010910430.22901@router.home>
On 06/01/2011 07:13 AM, Christoph Lameter wrote:
>>
>> Per your own description:
>>
>> "CMPXCHG_DOUBLE only compiles in detection support. It needs to be set
>> if there is a chance that processor supports these instructions."
>>
>> That condition is always TRUE, so no Kconfig is needed.
>
> There are several early processors (especially from AMD it seems) that do
> not support cmpxchg16b. If one builds a kernel specifically for the early
> cpus then the support does not need to be enabled.
>
We don't support building kernels specifically for those early CPUs as
far as I know. Besides, it is a very small set. Even if we did, the
conditional as you have specified it is wrong, and I mean "not even in
the general ballpark of correct".
> This is also an issue going beyond x86. Other platforms mostly do not
> support double word cmpxchg so the code for this feature also does not
> need to be included for those builds.
That's fine; just set it unconditionally for x86.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
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next prev parent reply other threads:[~2011-06-01 15:48 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-16 20:26 [slubllv5 00/25] SLUB: Lockless freelists for objects V5 Christoph Lameter
2011-05-16 20:26 ` [slubllv5 01/25] slub: Avoid warning for !CONFIG_SLUB_DEBUG Christoph Lameter
2011-05-16 20:26 ` [slubllv5 02/25] slub: Fix control flow in slab_alloc Christoph Lameter
2011-05-16 20:26 ` [slubllv5 03/25] slub: Make CONFIG_PAGE_ALLOC work with new fastpath Christoph Lameter
2011-05-17 4:52 ` Eric Dumazet
2011-05-17 13:46 ` Christoph Lameter
2011-05-17 19:22 ` Pekka Enberg
2011-05-16 20:26 ` [slubllv5 04/25] slub: Push irq disable into allocate_slab() Christoph Lameter
2011-05-16 20:26 ` [slubllv5 05/25] slub: Do not use frozen page flag but a bit in the page counters Christoph Lameter
2011-05-16 20:26 ` [slubllv5 06/25] slub: Move page->frozen handling near where the page->freelist handling occurs Christoph Lameter
2011-05-16 20:26 ` [slubllv5 07/25] x86: Add support for cmpxchg_double Christoph Lameter
2011-05-26 17:57 ` Pekka Enberg
2011-05-26 18:02 ` Christoph Lameter
2011-05-26 18:05 ` H. Peter Anvin
2011-05-26 18:17 ` Christoph Lameter
2011-05-26 18:29 ` H. Peter Anvin
2011-05-26 18:42 ` Christoph Lameter
2011-05-26 21:16 ` Christoph Lameter
2011-05-26 21:21 ` H. Peter Anvin
2011-05-26 21:25 ` Eric Dumazet
2011-05-26 21:31 ` H. Peter Anvin
2011-05-26 21:45 ` Eric Dumazet
2011-05-27 0:49 ` H. Peter Anvin
2011-05-31 15:13 ` Christoph Lameter
2011-05-31 15:16 ` H. Peter Anvin
2011-05-31 16:53 ` Christoph Lameter
2011-05-31 23:16 ` H. Peter Anvin
2011-05-31 23:49 ` Christoph Lameter
2011-05-31 23:54 ` H. Peter Anvin
2011-06-01 14:13 ` Christoph Lameter
2011-06-01 14:46 ` Christoph Lameter
2011-06-01 15:42 ` H. Peter Anvin
2011-06-01 16:08 ` Christoph Lameter
2011-06-01 15:41 ` H. Peter Anvin [this message]
2011-05-27 0:50 ` H. Peter Anvin
2011-05-31 15:10 ` Christoph Lameter
2011-05-16 20:26 ` [slubllv5 08/25] mm: Rearrange struct page Christoph Lameter
2011-05-16 20:26 ` [slubllv5 09/25] slub: Add cmpxchg_double_slab() Christoph Lameter
2011-05-16 20:26 ` [slubllv5 10/25] slub: explicit list_lock taking Christoph Lameter
2011-05-16 20:26 ` [slubllv5 11/25] slub: Pass kmem_cache struct to lock and freeze slab Christoph Lameter
2011-05-16 20:26 ` [slubllv5 12/25] slub: Rework allocator fastpaths Christoph Lameter
2011-05-16 20:26 ` [slubllv5 13/25] slub: Invert locking and avoid slab lock Christoph Lameter
2011-05-16 20:26 ` [slubllv5 14/25] slub: Disable interrupts in free_debug processing Christoph Lameter
2011-05-16 20:26 ` [slubllv5 15/25] slub: Avoid disabling interrupts in free slowpath Christoph Lameter
2011-05-16 20:26 ` [slubllv5 16/25] slub: Get rid of the another_slab label Christoph Lameter
2011-05-16 20:26 ` [slubllv5 17/25] slub: Add statistics for the case that the current slab does not match the node Christoph Lameter
2011-05-16 20:26 ` [slubllv5 18/25] slub: fast release on full slab Christoph Lameter
2011-05-16 20:26 ` [slubllv5 19/25] slub: Not necessary to check for empty slab on load_freelist Christoph Lameter
2011-05-16 20:26 ` [slubllv5 20/25] slub: slabinfo update for cmpxchg handling Christoph Lameter
2011-05-16 20:26 ` [slubllv5 21/25] slub: Prepare inuse field in new_slab() Christoph Lameter
2011-05-16 20:26 ` [slubllv5 22/25] slub: pass kmem_cache_cpu pointer to get_partial() Christoph Lameter
2011-05-16 20:26 ` [slubllv5 23/25] slub: return object pointer from get_partial() / new_slab() Christoph Lameter
2011-05-16 20:26 ` [slubllv5 24/25] slub: Remove gotos from __slab_free() Christoph Lameter
2011-05-16 20:26 ` [slubllv5 25/25] slub: Remove gotos from __slab_alloc() Christoph Lameter
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