Messages in this thread | | | Date | Tue, 03 Jan 2006 23:14:04 +0100 | From | Eric Dumazet <> | Subject | Re: [PATCH] [RFC] Optimize select/poll by putting small data sets on the stack |
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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
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