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

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Date:	Mon, 26 Feb 2007 13:43:02 +0300
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Davide Libenzi <davidel@...ilserver.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.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>,
	Ulrich Drepper <drepper@...hat.com>,
	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 Mon, Feb 26, 2007 at 11:31:17AM +0100, Ingo Molnar (mingo@...e.hu) wrote:
> 
> * Ingo Molnar <mingo@...e.hu> wrote:
> 
> > please also try evserver_epoll_threadlet.c that i've attached below - 
> > it uses epoll as the main event mechanism but does threadlets for 
> > request handling.
> 
> find updated code below - your evserver_epoll.c spuriously missed event 
> edges - so i changed it back to level-triggered. While that is not as 
> fast as edge-triggered, it does not result in spurious hangs and 
> workflow 'hickups' during the test.

Hmm, exact the same evserver_epoll.c you downloaded works ok for me,
although yes, it is buggy in that regard that it does not contain socket
close when data is transferred.

> Could this be the reason why in your testing kevents outperformed epoll?

I will try to check. In theory without _ET it should perfoem much worse,
but in practice its performance is essentially the same (the same applies 
to kevent without KEVENT_REQ_ET flag - since the same socket almost never 
is used several times, it is purely zero overhead to have or not have that 
flag set).

> Also, i have removed the set-nonblocking calls because they are not 
> needed under threadlets.
> 
> [ to build this code, copy it into the async-test/ directory and build
>   it there - or copy the *.h files from async-test/ directory into your
>   build directory. ]

Ok, right now I'm compiling kevent/threadlet tree on my test machines.

> 	Ingo

-- 
	Evgeniy Polyakov
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