From: Ingo Molnar <mingo@elte.hu>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Pekka Enberg <penberg@cs.helsinki.fi>,
Christoph Lameter <christoph@lameter.com>,
Alok N Kataria <alokk@calsoftinc.com>,
Shobhit Dayal <shobhit@calsoftinc.com>,
Shai Fultheim <shai@scalex86.org>, Matt Mackall <mpm@selenic.com>,
Andrew Morton <akpm@osdl.org>, john stultz <johnstul@us.ibm.com>,
Gunter Ohrner <G.Ohrner@post.rwth-aachen.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RT 00/02] SLOB optimizations
Date: Wed, 21 Dec 2005 08:43:46 +0100 [thread overview]
Message-ID: <20051221074346.GA2398@elte.hu> (raw)
In-Reply-To: <43A90225.4060007@cosmosbay.com>
* Eric Dumazet <dada1@cosmosbay.com> wrote:
> >while it could possibly be cleaned up a bit, it's one of the
> >best-optimized subsystems Linux has. Most of the "unnecessary
> >complexity" in SLAB is related to a performance or a debugging feature.
> >Many times i have looked at the SLAB code in a disassembler, right next
> >to profile output from some hot workload, and have concluded: 'I couldnt
> >do this any better even with hand-coded assembly'.
>
> Well, I miss a version of kmem_cache_alloc()/kmem_cache_free() that
> wont play with IRQ masking.
sure, but adding this sure wont reduce complexity ;)
> The local_irq_save()/local_irq_restore() pair is quite expensive and
> could be avoided for several caches that are exclusively used in
> process context.
in any case, on sane platforms (i386, x86_64) an irq-disable is
well-optimized in hardware, and is just as fast as a preempt_disable().
Combined with the fact that CLI/STI has no register side-effects, it can
even be faster/cheaper, on x86 at least.
Ingo
next prev parent reply other threads:[~2005-12-21 7:44 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-16 11:30 2.6.15-rc5-rt2 slowness Gunter Ohrner
2005-12-16 11:42 ` Gunter Ohrner
2005-12-16 12:04 ` Gunter Ohrner
2005-12-16 12:34 ` Steven Rostedt
2005-12-16 12:32 ` Steven Rostedt
2005-12-16 22:58 ` john stultz
2005-12-17 0:22 ` Gunter Ohrner
2005-12-17 3:51 ` Steven Rostedt
2005-12-17 3:33 ` Steven Rostedt
2005-12-17 22:57 ` Steven Rostedt
2005-12-18 16:05 ` K.R. Foley
2005-12-20 13:32 ` Ingo Molnar
2005-12-20 13:38 ` Steven Rostedt
2005-12-20 13:57 ` Ingo Molnar
2005-12-20 14:04 ` Steven Rostedt
2005-12-20 14:33 ` Steven Rostedt
2005-12-20 15:07 ` Ingo Molnar
2005-12-20 15:16 ` Steven Rostedt
2005-12-20 15:44 ` [PATCH RT 00/02] SLOB optimizations Steven Rostedt
2005-12-20 15:56 ` Steven Rostedt
2005-12-20 15:58 ` Ingo Molnar
2005-12-20 16:13 ` Ingo Molnar
2005-12-20 16:29 ` Steven Rostedt
2005-12-20 16:39 ` Steven Rostedt
2005-12-20 18:19 ` Matt Mackall
2005-12-20 19:15 ` Steven Rostedt
2005-12-20 19:43 ` Matt Mackall
2005-12-20 20:06 ` Steven Rostedt
2005-12-20 20:15 ` Pekka Enberg
2005-12-20 21:42 ` Steven Rostedt
2005-12-20 21:52 ` Christoph Lameter
2005-12-20 22:11 ` Steven Rostedt
2005-12-21 6:36 ` Ingo Molnar
2005-12-21 12:50 ` Steven Rostedt
2005-12-21 6:56 ` Ingo Molnar
2005-12-21 7:16 ` Pekka J Enberg
2005-12-21 7:50 ` Ingo Molnar
2005-12-21 13:13 ` Steven Rostedt
2005-12-21 15:34 ` [PATCH] SLAB - have index_of bug at compile time Steven Rostedt
2005-12-21 7:20 ` [PATCH RT 00/02] SLOB optimizations Eric Dumazet
2005-12-21 7:43 ` Ingo Molnar [this message]
2005-12-21 8:02 ` Eric Dumazet
2005-12-22 18:02 ` Zwane Mwaikambo
2005-12-22 21:11 ` Ingo Molnar
2005-12-22 21:39 ` Eric Dumazet
2005-12-22 21:44 ` George Anzinger
2005-12-22 22:00 ` Eric Dumazet
2005-12-22 22:08 ` Eric Dumazet
2005-12-23 19:22 ` Zwane Mwaikambo
2005-12-21 13:02 ` Steven Rostedt
2005-12-21 2:30 ` Nick Piggin
2005-12-21 2:41 ` Steven Rostedt
2005-12-20 15:44 ` [PATCH RT 01/02] SLOB - remove bigblock list Steven Rostedt
2005-12-20 15:44 ` [PATCH RT 02/02] SLOB - break SLOB up by caches Steven Rostedt
2005-12-20 14:07 ` 2.6.15-rc5-rt2 slowness Steven Rostedt
2005-12-20 15:26 ` K.R. Foley
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