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Re: Linux 2.6.25-rc2

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To: Andrew Morton <akpm@...>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...>, Pekka Enberg <penberg@...>, Torsten Kaiser <just.for.lkml@...>, Ingo Molnar <mingo@...>, Linus Torvalds <torvalds@...>, Linux Kernel Mailing List <linux-kernel@...>, Eric Dumazet <dada1@...>
Date: Wednesday, February 27, 2008 - 10:43 pm

On Wed, 27 Feb 2008, Andrew Morton wrote:


local_t requires the disabling of preempt to work right.

The real solution here is cpu_alloc / cpu_ops. Per cpu operations work on 
an offset relative to the start of the per process cpu data area in some 
register. An increment can then be atomic vs. interrupt because it does 
the calculation of the address and the inc in one instruction. F.e.

gs: inc [percpu_offset]

Processor may change before and after without ill effects. So no preempt 
since the instruction will always reference the %%gs register that points 
to the percpu area of the currently executing processor.
--
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Messages in current thread:
Linux 2.6.25-rc2, Linus Torvalds, (Fri Feb 15, 5:23 pm)
Re: Linux 2.6.25-rc2, Torsten Kaiser, (Sat Feb 16, 5:38 pm)
Re: Linux 2.6.25-rc2, Ingo Molnar, (Tue Feb 19, 2:11 am)
Re: Linux 2.6.25-rc2, Torsten Kaiser, (Tue Feb 19, 2:54 am)
Re: Linux 2.6.25-rc2, Pekka Enberg, (Tue Feb 19, 3:21 am)
Re: Linux 2.6.25-rc2, Mathieu Desnoyers, (Tue Feb 19, 10:02 am)
Re: Linux 2.6.25-rc2, Torsten Kaiser, (Tue Feb 19, 2:39 pm)
Re: Linux 2.6.25-rc2, Eric Dumazet, (Tue Feb 19, 12:27 pm)
Re: Linux 2.6.25-rc2, Christoph Lameter, (Wed Feb 27, 7:32 pm)
Re: Linux 2.6.25-rc2, Mathieu Desnoyers, (Tue Feb 19, 4:03 pm)
Re: Linux 2.6.25-rc2, Christoph Lameter, (Wed Feb 27, 7:34 pm)
[PATCH] Implement slub fastpath in terms of freebase and fre..., Mathieu Desnoyers, (Thu Feb 28, 1:55 am)
Re: [PATCH] Implement slub fastpath in terms of freebase and..., Christoph Lameter, (Thu Feb 28, 3:08 pm)
Re: [PATCH] Implement slub fastpath in terms of freebase and..., Mathieu Desnoyers, (Thu Feb 28, 7:25 pm)
Re: [PATCH] Implement slub fastpath in terms of freebase and..., Christoph Lameter, (Thu Feb 28, 8:57 pm)
Re: [PATCH] Implement slub fastpath in terms of freebase and..., Mathieu Desnoyers, (Thu Feb 28, 9:56 pm)
Re: [PATCH] Implement slub fastpath in terms of freebase and..., Christoph Lameter, (Thu Feb 28, 10:12 pm)
Re: [PATCH] Implement slub fastpath in terms of freebase and..., Mathieu Desnoyers, (Thu Feb 28, 11:32 pm)
Re: [PATCH] Implement slub fastpath in terms of freebase and..., Christoph Lameter, (Fri Feb 29, 1:11 am)
[PATCH] Slub Freeoffset check overflow, Mathieu Desnoyers, (Fri Feb 29, 9:28 am)
[PATCH] Slub Freeoffset check overflow (updated), Mathieu Desnoyers, (Tue Mar 4, 2:17 am)
Re: [PATCH] Slub Freeoffset check overflow (updated), Christoph Lameter, (Tue Mar 4, 3:15 am)
Re: [PATCH] Implement slub fastpath in terms of freebase and..., Mathieu Desnoyers, (Fri Feb 29, 9:03 am)
Re: [PATCH] Implement slub fastpath in terms of freebase and..., Christoph Lameter, (Fri Feb 29, 3:57 pm)
Re: Linux 2.6.25-rc2, Linus Torvalds, (Tue Feb 19, 12:38 pm)
Re: Linux 2.6.25-rc2, Pekka Enberg, (Tue Feb 19, 10:21 am)
Re: Linux 2.6.25-rc2, Mathieu Desnoyers, (Tue Feb 19, 4:08 pm)
Re: Linux 2.6.25-rc2, Christoph Lameter, (Wed Feb 27, 7:32 pm)
Re: Linux 2.6.25-rc2, Andrew Morton, (Wed Feb 27, 9:57 pm)
Re: Linux 2.6.25-rc2, Jiri Kosina, (Thu Feb 28, 7:13 am)
Re: Linux 2.6.25-rc2, Ingo Molnar, (Thu Feb 28, 4:14 am)
Re: Linux 2.6.25-rc2, Alan Cox, (Thu Feb 28, 7:15 am)
Re: Linux 2.6.25-rc2, Christoph Lameter, (Wed Feb 27, 10:43 pm)
Re: Linux 2.6.25-rc2, Pekka Enberg, (Tue Feb 19, 10:38 am)
Re: Linux 2.6.25-rc2, Linus Torvalds, (Tue Feb 19, 12:20 pm)
Re: Linux 2.6.25-rc2, Torsten Kaiser, (Tue Feb 19, 3:27 pm)
Re: Linux 2.6.25-rc2, Ingo Molnar, (Tue Feb 19, 12:45 pm)
Re: Linux 2.6.25-rc2, Ingo Molnar, (Tue Feb 19, 12:48 pm)
Re: Linux 2.6.25-rc2, Ingo Molnar, (Tue Feb 19, 10:55 am)
Re: Linux 2.6.25-rc2, Pekka Enberg, (Tue Feb 19, 11:52 am)
Re: Linux 2.6.25-rc2, Zhang, Yanmin, (Tue Feb 19, 8:36 pm)
Re: Linux 2.6.25-rc2, Zhang, Yanmin, (Tue Feb 19, 10:08 pm)
Re: Linux 2.6.25-rc2, Zhang, Yanmin, (Wed Feb 20, 2:53 am)
Re: Linux 2.6.25-rc2, Pekka Enberg, (Wed Feb 20, 3:10 am)
Re: Linux 2.6.25-rc2, Ingo Molnar, (Tue Feb 19, 10:57 am)
Re: Linux 2.6.25-rc2, Pekka Enberg, (Tue Feb 19, 11:54 am)
Re: Linux 2.6.25-rc2, Ingo Molnar, (Tue Feb 19, 6:27 am)
Re: Linux 2.6.25-rc2, Mathieu Desnoyers, (Tue Feb 19, 9:02 am)
Re: Linux 2.6.25-rc2, Ingo Molnar, (Tue Feb 19, 10:00 am)
Re: Linux 2.6.25-rc2, Pekka Enberg, (Tue Feb 19, 6:45 am)
Re: Linux 2.6.25-rc2, Linus Torvalds, (Mon Feb 18, 7:54 pm)
Re: Linux 2.6.25-rc2, Torsten Kaiser, (Tue Feb 19, 2:44 am)
Re: Linux 2.6.25-rc2, Rafael J. Wysocki, (Sun Feb 17, 4:25 pm)
Re: Linux 2.6.25-rc2, Torsten Kaiser, (Sun Feb 17, 5:32 pm)
Linux 2.6.25-rc2 regression: LVM cannot find volume group, Tilman Schmidt, (Sat Feb 16, 3:14 pm)
Re: Linux 2.6.25-rc2 regression: LVM cannot find volume group, Alasdair G Kergon, (Mon Feb 18, 9:53 pm)
Re: Linux 2.6.25-rc2, Jan Engelhardt, (Sat Feb 16, 12:52 pm)
Re: [BUG] Linux 2.6.25-rc2 - Regression from 2.6.24-rc1-git1..., Rafael J. Wysocki, (Sun Feb 17, 4:08 pm)
Re: [BUG] Linux 2.6.25-rc2 - Regression from 2.6.24-rc1-git1..., KAMEZAWA Hiroyuki, (Tue Feb 19, 4:04 am)
Re: [BUG] Linux 2.6.25-rc2 - Regression from 2.6.24-rc1-git1..., KAMEZAWA Hiroyuki, (Tue Feb 19, 5:02 am)
Re: [BUG] Linux 2.6.25-rc2 - Regression from 2.6.24-rc1-git1..., KAMEZAWA Hiroyuki, (Tue Feb 19, 4:47 am)
Re: [BUG] Linux 2.6.25-rc2 - Regression from 2.6.24-rc1-git1..., KAMEZAWA Hiroyuki, (Tue Feb 19, 5:07 am)
[BUG] Linux 2.6.25-rc2 - Kernel Ooops while running dbench, Kamalesh Babulal, (Sat Feb 16, 1:44 am)
Re: Linux 2.6.25-rc2, Rafael J. Wysocki, (Fri Feb 15, 10:08 pm)
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