linux-kernel - Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3

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Date:	Thu, 1 Mar 2007 17:54:54 +0300
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Eric Dumazet <dada1@...mosbay.com>, Pavel Machek <pavel@....cz>,
	Theodore Tso <tytso@....edu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ulrich Drepper <drepper@...hat.com>,
	linux-kernel@...r.kernel.org,
	Arjan van de Ven <arjan@...radead.org>,
	Christoph Hellwig <hch@...radead.org>,
	Andrew Morton <akpm@....com.au>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Zach Brown <zach.brown@...cle.com>,
	"David S. Miller" <davem@...emloft.net>,
	Suparna Bhattacharya <suparna@...ibm.com>,
	Davide Libenzi <davidel@...ilserver.org>,
	Jens Axboe <jens.axboe@...cle.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3

On Thu, Mar 01, 2007 at 03:16:37PM +0100, Ingo Molnar (mingo@...e.hu) wrote:
> 
> * Eric Dumazet <dada1@...mosbay.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
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