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

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Message-ID: <20070302081047.GA27122@2ka.mipt.ru>
Date:	Fri, 2 Mar 2007 11:10:48 +0300
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	Davide Libenzi <davidel@...ilserver.org>
Cc:	Ingo Molnar <mingo@...e.hu>, 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 Mailing List <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>,
	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 11:31:14AM -0800, Davide Libenzi (davidel@...ilserver.org) wrote:
> On Thu, 1 Mar 2007, Evgeniy Polyakov wrote:
> 
> > Ingo, do you really think I will send mails with faked benchmarks? :))
> 
> I don't think he ever implied that. He was only suggesting that when you 
> post benchmarks, and even more when you make claims based on benchmarks, 
> you need to be extra carefull about what you measure. Otherwise the 
> external view that you give to others does not look good.
> Kevent can be really faster than epoll, but if you post broken benchmarks 
> (that can be, unrealiable HTTP loaders, broken server implemenations, 
> etc..) and make claims based on that, the only effect that you have is to 
> lose your point.

We seems to move far away from original topic - I never built any
assumptions on top of kevent _performance_ - kevent is a logical
extrapolation of the epoll, I only showed that event driven model can be
fast and it outperforms threadlet one - after we changed topic we were
unable to actually test threadlets in networking environment, since the
only test I ran showed that threadlest do not reschedule at all, and
Ingo's tests showed small number of reschedulings.

So, I only talked that kevent is superior compared to epoll because (and
it is _main_ issue) of its ability to handle essentially any kind of
events with very small overhead (the same as epoll has in struct file -
list and spinlock) and without significant price of struct file binding
to event.

I did not want and do not want to hurt anyone (even Ingo, although he is 
against kevent :), but my opinion is that thread moved from nice 
discussion about threads and events with jokes and fun into quite angry 
word throwings, and that is too good - let's make it fun again.
I'm not a native english speaker (and do not use a dictionary), so it is 
quite possible that some my phrases were not exactly nice, but it was 
unintentional (at least not very) :)

Peace?

> - Davide
> 

-- 
	Evgeniy Polyakov
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