Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932117AbXBVONJ (ORCPT ); Thu, 22 Feb 2007 09:13:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932081AbXBVONJ (ORCPT ); Thu, 22 Feb 2007 09:13:09 -0500 Received: from e6.ny.us.ibm.com ([32.97.182.146]:57882 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933079AbXBVONH (ORCPT ); Thu, 22 Feb 2007 09:13:07 -0500 Date: Thu, 22 Feb 2007 19:47:26 +0530 From: Suparna Bhattacharya To: Ingo Molnar Cc: Evgeniy Polyakov , Ulrich Drepper , linux-kernel@vger.kernel.org, Linus Torvalds , Arjan van de Ven , Christoph Hellwig , Andrew Morton , Alan Cox , Zach Brown , "David S. Miller" , Davide Libenzi , Jens Axboe , Thomas Gleixner Subject: Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3 Message-ID: <20070222141726.GA31874@in.ibm.com> Reply-To: suparna@in.ibm.com References: <20070221211355.GA7302@elte.hu> <20070221233111.GB5895@elte.hu> <45DCD9E5.2010106@redhat.com> <20070222074044.GA4158@elte.hu> <20070222113148.GA3781@2ka.mipt.ru> <20070222125931.GB25788@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070222125931.GB25788@elte.hu> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2081 Lines: 50 On Thu, Feb 22, 2007 at 01:59:31PM +0100, Ingo Molnar wrote: > > * Evgeniy Polyakov wrote: > > > It is not a TUX anymore - you had 1024 threads, and all of them will > > be consumed by tcp_sendmsg() for slow clients - rescheduling will kill > > a machine. > > maybe it will, maybe it wont. Lets try? There is no true difference > between having a 'request structure' that represents the current state > of the HTTP connection plus a statemachine that moves that request > between various queues, and a 'kernel stack' that goes in and out of > runnable state and carries its processing state in its stack - other > than the amount of RAM they take. (the kernel stack is 4K at a minimum - > so with a million outstanding requests they would use up 4 GB of RAM. > With 20k outstanding requests it's 80 MB of RAM - that's acceptable.) At what point are the cachemiss threads destroyed ? In other words how well does this adapt to load variations ? For example, would this 80MB of RAM continue to be locked down even during periods of lighter loads thereafter ? Regards Suparna > > > My tests show that with 4k connections per second (8k concurrency) > > more than 20k connections of 80k total block in tcp_sendmsg() over > > gigabit lan between quite fast machines. > > yeah. Note that you can have a million sleeping threads if you want, the > scheduler wont care. What matters more is the amount of true concurrency > that is present at any given time. But yes, i agree that overscheduling > can be a problem. > > btw., what is the measurement utility you are using with kevents ('ab' > perhaps, with a high -c concurrency count?), and which webserver are you > using? (light-httpd?) > > Ingo -- Suparna Bhattacharya (suparna@in.ibm.com) Linux Technology Center IBM Software Lab, India - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/