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Date: Thu, 1 Mar 2007 15:47:17 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
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
Message-ID: <20070301144717.GA24079@elte.hu>
References: <Pine.LNX.4.64.0702260938450.12485@woody.linux-foundation.org> <200703011228.01144.dada1@cosmosbay.com> <20070301114731.GA20773@2ka.mipt.ru> <200703011412.51256.dada1@cosmosbay.com> <20070301144350.GA12684@2ka.mipt.ru>
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* Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:

> CPU: AMD64 processors, speed 2210.08 MHz (estimated)
> Counted CPU_CLK_UNHALTED events (Cycles outside of halt state) with a unit mask of 0x00 (No unit mask) count 100000
> samples  %        symbol name
> 195750   67.3097  cpu_idle
> 14111     4.8521  enter_idle
> 4979      1.7121  IRQ0x51_interrupt
> 4765      1.6385  tcp_v4_rcv

the pretty much only meaningful way to measure this is to:

- start a really long 'ab' testrun. Something like "ab -c 8000 -t 600".
- let the system get into 'steady state': i.e. CPU load at 100%
- reset the oprofile counters, then start an oprofile run for 60 
  seconds.
- stop the oprofile run.
- stop the test.

this way there wont be that many 'cpu_idle' entries in your profiles, 
and the profiles between the two event delivery mechanisms will be 
directly comparable.

> In that tests I got epoll perf about 4400 req/s, kevent was about 
> 5300.

So we are now up to epoll being 83% of kevent's performance - while the 
noise of numbers seen today alone is around 100% ... Could you update 
the files two URLs that you posted before, with the code that you used 
for the above numbers:

   http://tservice.net.ru/~s0mbre/archive/kevent/evserver_epoll.c
   http://tservice.net.ru/~s0mbre/archive/kevent/evserver_kevent.c

thanks,

	Ingo