From: Eric Dumazet <dada1@cosmosbay.com>
To: Andi Kleen <ak@suse.de>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] [RFC] Optimize select/poll by putting small data sets on the stack
Date: Tue, 03 Jan 2006 23:14:04 +0100 [thread overview]
Message-ID: <43BAF72C.2030608@cosmosbay.com> (raw)
In-Reply-To: <200601032158.14057.ak@suse.de>
Andi Kleen a écrit :
> This is a RFC for now. I would be interested in testing
> feedback. Patch is for 2.6.15.
>
> Optimize select and poll by a using stack space for small fd sets
>
> This brings back an old optimization from Linux 2.0. Using
> the stack is faster than kmalloc. On a Intel P4 system
> it speeds up a select of a single pty fd by about 13%
> (~4000 cycles -> ~3500)
Was this result on UP or SMP kernel ? Preempt or not ?
I think we might play in do_pollfd() and use fget_light()/fput_light() instead
of fget()/fput() that are somewhat expensive because of atomic inc/dec on SMP.
(I believe that select()/poll() based daemons are mostly non multi-threaded,
since high performance multi-threaded programs should be using epoll...)
Eric
next prev parent reply other threads:[~2006-01-03 22:14 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-03 20:58 [PATCH] [RFC] Optimize select/poll by putting small data sets on the stack Andi Kleen
2006-01-03 22:14 ` Eric Dumazet [this message]
2006-01-03 23:05 ` Andi Kleen
2006-01-03 23:07 ` Eric Dumazet
2006-01-03 23:13 ` Andi Kleen
2006-01-03 22:22 ` Jesper Juhl
2006-01-03 23:07 ` Andi Kleen
2006-01-04 0:28 ` Arnd Bergmann
2006-01-04 0:33 ` Andi Kleen
2006-01-04 0:43 ` Eric Dumazet
2006-01-04 0:48 ` Andi Kleen
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