From: Ingo Molnar <mingo@elte.hu>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
akpm@linux-foundation.org, tj@kernel.org, hpa@zytor.com,
brgerst@gmail.com, ebiederm@xmission.com,
cl@linux-foundation.org, travis@sgi.com,
linux-kernel@vger.kernel.org, steiner@sgi.com, hugh@veritas.com
Subject: Re: [PATCH] percpu: add optimized generic percpu accessors
Date: Fri, 16 Jan 2009 23:09:25 +0100 [thread overview]
Message-ID: <20090116220925.GA28917@elte.hu> (raw)
In-Reply-To: <200901170804.18622.rusty@rustcorp.com.au>
* Rusty Russell <rusty@rustcorp.com.au> wrote:
> On Friday 16 January 2009 10:42:00 Herbert Xu wrote:
> > Ingo Molnar <mingo@elte.hu> wrote:
> > >
> > >> Of course. But do any architectures actually _need_ that for a single
> > >> read?
> > >
> > > not for a read i guess - but for the other ops like add/and/or/xor.
> >
> > One of the things I'd like to see happen with this work is for
> > us to have a cheap per-cpu atomic counter that we can use for
> > SNMP stats.
> >
> > If we can make the inc/add variants into a single instruction, then it
> > won't need to disable preemption or interrupts.
> >
> > So if you could design the API such that we have a variant of add/inc
> > that automatically disables/enables preemption then we can optimise
> > that away on x86.
>
> Yep, already on it. It's called local_t; that's what it was originally
> designed for.
>
> Unfortunately, to use it efficiently, we need large per-cpu areas.
This makes no sense to me at all. Care to explain?
Ingo
next prev parent reply other threads:[~2009-01-16 22:11 UTC|newest]
Thread overview: 113+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-13 10:38 [PATCHSET linux-2.6-x86:tip] x86: make percpu offsets zero-based on SMP Tejun Heo
2009-01-13 10:38 ` [PATCH 01/13] x86_64: fix pda_to_op() Tejun Heo
2009-01-13 10:38 ` [PATCH 02/13] x86: make early_per_cpu() a lvalue and use it Tejun Heo
2009-01-13 11:43 ` [PATCH 02/13 UPDATED] " Tejun Heo
2009-01-13 10:38 ` [PATCH 03/13] x86_64: Cleanup early setup_percpu references Tejun Heo
2009-01-13 10:38 ` [PATCH 04/13] x86_32: make vmlinux_32.lds.S use PERCPU() macro Tejun Heo
2009-01-13 10:38 ` [PATCH 05/13] x86_64: make percpu symbols zerobased on SMP Tejun Heo
2009-01-13 10:38 ` [PATCH 06/13] x86_64: load pointer to pda into %gs while brining up a CPU Tejun Heo
2009-01-13 10:38 ` [PATCH 07/13] x86_64: use static _cpu_pda array Tejun Heo
2009-01-13 10:38 ` [PATCH 08/13] x86_64: fold pda into percpu area on SMP Tejun Heo
2009-01-13 10:38 ` [PATCH 09/13] x86_64: merge 64 and 32 SMP percpu handling Tejun Heo
2009-01-13 10:38 ` [PATCH 10/13] x86_64: make pda a percpu variable Tejun Heo
2009-01-13 10:38 ` [PATCH 11/13] x86_64: convert pda ops to wrappers around x86 percpu accessors Tejun Heo
2009-01-13 10:38 ` [PATCH 12/13] x86_64: misc clean up after the percpu update Tejun Heo
2009-01-13 10:38 ` [PATCH 13/13] x86_32: make percpu symbols zerobased on SMP Tejun Heo
2009-01-14 0:18 ` Rusty Russell
2009-01-14 2:03 ` Tejun Heo
2009-01-13 10:48 ` [PATCHSET linux-2.6-x86:tip] x86: make percpu offsets zero-based " Tejun Heo
2009-01-13 13:27 ` Brian Gerst
2009-01-13 14:05 ` Tejun Heo
2009-01-13 14:26 ` Brian Gerst
2009-01-13 14:37 ` Tejun Heo
2009-01-14 6:57 ` H. Peter Anvin
2009-01-14 9:38 ` [patch] add optimized generic percpu accessors Ingo Molnar
2009-01-14 9:45 ` Ingo Molnar
2009-01-15 10:04 ` roel kluin
2009-01-15 10:26 ` Tejun Heo
2009-01-15 11:32 ` Ingo Molnar
2009-01-15 11:36 ` Tejun Heo
2009-01-15 12:22 ` Ingo Molnar
2009-01-15 13:09 ` Tejun Heo
2009-01-15 13:32 ` Ingo Molnar
2009-01-15 13:33 ` Ingo Molnar
2009-01-15 13:39 ` Ingo Molnar
2009-01-15 21:54 ` Tejun Heo
2009-01-16 1:28 ` [PATCH x86/percpu] x86: fix build bug introduced during merge Tejun Heo
2009-01-16 3:25 ` [PATCH x86/percpu] x86_64: initialize this_cpu_off to __per_cpu_load Tejun Heo
2009-01-16 13:16 ` Ingo Molnar
2009-01-16 13:47 ` Tejun Heo
[not found] ` <20090116221651.GA32736@elte.hu>
[not found] ` <20090116223828.GA9294@elte.hu>
[not found] ` <49716F0E.7060605@gmail.com>
[not found] ` <49716FBF.7080203@kernel.org>
2009-01-17 6:29 ` [PATCH core/percpu REPOST] linker script: add missing VMLINUX_SYMBOL Tejun Heo
2009-01-17 6:32 ` [PATCH] linker script: add missing .data.percpu.page_aligned Tejun Heo
2009-01-17 8:21 ` Ingo Molnar
2009-01-21 23:46 ` Christoph Lameter
2009-01-21 23:45 ` [PATCH core/percpu REPOST] linker script: add missing VMLINUX_SYMBOL Christoph Lameter
2009-01-15 22:34 ` [patch] add optimized generic percpu accessors Ingo Molnar
2009-01-15 20:31 ` Christoph Lameter
2009-01-16 9:41 ` Tejun Heo
2009-01-16 13:23 ` Ingo Molnar
2009-01-16 13:49 ` Tejun Heo
2009-01-15 10:26 ` Tejun Heo
2009-01-15 11:30 ` Ingo Molnar
2009-01-15 11:38 ` Tejun Heo
2009-01-15 12:26 ` Ingo Molnar
2009-01-15 13:04 ` Tejun Heo
2009-01-15 13:07 ` Ingo Molnar
2009-01-15 13:23 ` [PATCH] percpu: " Tejun Heo
2009-01-15 13:36 ` Ingo Molnar
2009-01-15 17:30 ` Andrew Morton
2009-01-15 18:02 ` Ingo Molnar
2009-01-15 18:34 ` Andrew Morton
2009-01-15 18:39 ` Ingo Molnar
2009-01-15 21:53 ` Tejun Heo
2009-01-16 0:12 ` Herbert Xu
2009-01-16 0:15 ` Ingo Molnar
2009-01-16 0:18 ` Herbert Xu
[not found] ` <200901170827.33729.rusty@rustcorp.com.au>
2009-01-16 22:08 ` Ingo Molnar
[not found] ` <200901201328.24605.rusty@rustcorp.com.au>
2009-01-20 6:25 ` Tejun Heo
2009-01-20 10:36 ` Ingo Molnar
[not found] ` <200901271213.18605.rusty@rustcorp.com.au>
2009-01-27 2:24 ` Tejun Heo
2009-01-27 13:13 ` Ingo Molnar
2009-01-27 23:07 ` Tejun Heo
2009-01-28 3:36 ` Tejun Heo
2009-01-28 8:12 ` Tejun Heo
2009-01-27 20:08 ` Christoph Lameter
2009-01-27 21:47 ` David Miller
2009-01-27 22:47 ` Rick Jones
2009-01-27 22:47 ` Rick Jones
2009-01-28 0:17 ` Luck, Tony
2009-01-28 0:17 ` Luck, Tony
2009-01-28 16:48 ` Christoph Lameter
2009-01-28 16:48 ` Christoph Lameter
2009-01-28 17:15 ` Luck, Tony
2009-01-28 17:15 ` Luck, Tony
2009-01-28 16:45 ` Christoph Lameter
2009-01-28 20:47 ` David Miller
2009-01-28 10:38 ` Rusty Russell
2009-01-28 10:56 ` Tejun Heo
2009-01-29 2:06 ` Rusty Russell
2009-01-31 6:11 ` Tejun Heo
2009-01-28 16:50 ` Christoph Lameter
2009-01-28 18:07 ` Mathieu Desnoyers
2009-01-29 18:33 ` Christoph Lameter
2009-01-29 18:48 ` H. Peter Anvin
2009-01-20 10:40 ` Ingo Molnar
2009-01-21 5:52 ` Tejun Heo
2009-01-21 10:05 ` Ingo Molnar
2009-01-21 11:21 ` Eric W. Biederman
2009-01-21 12:45 ` Stephen Hemminger
2009-01-21 14:13 ` Eric W. Biederman
2009-01-21 20:34 ` David Miller
2009-01-16 1:09 ` H. Peter Anvin
[not found] ` <200901170804.18622.rusty@rustcorp.com.au>
2009-01-16 21:59 ` Ingo Molnar
2009-01-16 22:09 ` Ingo Molnar [this message]
2009-01-16 14:10 ` Mark Lord
2009-01-15 18:46 ` Ingo Molnar
2009-01-31 10:36 ` Jeremy Fitzhardinge
2009-01-15 13:59 ` [patch] " roel kluin
2009-01-15 21:51 ` Tejun Heo
[not found] ` <200901170748.53734.rusty@rustcorp.com.au>
2009-01-16 21:24 ` Ingo Molnar
[not found] ` <200901151253.44016.rusty@rustcorp.com.au>
2009-01-15 9:55 ` Ingo Molnar
2009-01-15 10:27 ` Tejun Heo
2009-01-31 10:30 ` Jeremy Fitzhardinge
2009-01-31 16:00 ` Ingo Molnar
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