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Date: Thu, 1 Mar 2007 17:54:54 +0300
From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
To: Ingo Molnar <mingo@elte.hu>
Cc: Eric Dumazet <dada1@cosmosbay.com>, Pavel Machek <pavel@ucw.cz>,
       Theodore Tso <tytso@mit.edu>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Ulrich Drepper <drepper@redhat.com>, linux-kernel@vger.kernel.org,
       Arjan van de Ven <arjan@infradead.org>,
       Christoph Hellwig <hch@infradead.org>, Andrew Morton <akpm@zip.com.au>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>, Zach Brown <zach.brown@oracle.com>,
       "David S. Miller" <davem@davemloft.net>,
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       Davide Libenzi <davidel@xmailserver.org>,
       Jens Axboe <jens.axboe@oracle.com>,
       Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3
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References: <20070301095402.GA14603@elte.hu> <20070301131118.GA30228@elte.hu> <20070301133018.GB30177@2ka.mipt.ru> <200703011519.20001.dada1@cosmosbay.com> <20070301141637.GA20006@elte.hu>
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On Thu, Mar 01, 2007 at 03:16:37PM +0100, Ingo Molnar (mingo@elte.hu) wrote:
> 
> * Eric Dumazet <dada1@cosmosbay.com> wrote:
> 
> > I can tell you that the problem (at least on my machine) comes from :
> > 
> > gettimeofday(&tm, NULL);
> > 
> > in evserver_epoll.c
> 
> yeah, that's another difference - especially if it's something like an 
> Athlon64 and gettimeofday falls back to pm-timer, that could explain the 
> performance difference. That's why i repeatedly asked Evgeniy to use the 
> /very same/ client function for both the epoll and the kevent test and 
> redo the measurements. The numbers are still highly suspect - and we are 
> already down from the prior claim of kevent being almost twice as fast 
> to a 25% difference.

There is no gettimeofday() in the running code anymore, and it was
placed not in common server processing code btw.

Ingo, do you really think I will send mails with faked benchmarks? :))

Btw, there were never almost twice perfromance increase - epoll in my
tests always showed 4-5 thousands requests per second, kevent - up to 7
thausands.

That starts looking like ghost hunting, Ingo, you already said that
you do not see any need in kevent, have you changed your opinion on
that?

> 	Ingo

-- 
	Evgeniy Polyakov