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

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Date:	Thu, 1 Mar 2007 15:47:17 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Evgeniy Polyakov <johnpol@....mipt.ru>
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


* Evgeniy Polyakov <johnpol@....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
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