Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753757AbXFYXjg (ORCPT ); Mon, 25 Jun 2007 19:39:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751792AbXFYXj3 (ORCPT ); Mon, 25 Jun 2007 19:39:29 -0400 Received: from einhorn.in-berlin.de ([192.109.42.8]:54287 "EHLO einhorn.in-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751517AbXFYXj3 (ORCPT ); Mon, 25 Jun 2007 19:39:29 -0400 X-Envelope-From: stefanr@s5r6.in-berlin.de Message-ID: <46805196.8070407@s5r6.in-berlin.de> Date: Tue, 26 Jun 2007 01:36:54 +0200 From: Stefan Richter User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.4) Gecko/20070609 SeaMonkey/1.1.2 MIME-Version: 1.0 To: Ingo Molnar CC: Kristian H?gsberg , Linus Torvalds , Steven Rostedt , LKML , Andrew Morton , Thomas Gleixner , Christoph Hellwig , john stultz , Oleg Nesterov , "Paul E. McKenney" , Dipankar Sarma , "David S. Miller" , matthew.wilcox@hp.com, kuznet@ms2.inr.ac.ru Subject: Re: [RFC PATCH 0/6] Convert all tasklets to workqueues References: <20070622040014.234651401@goodmis.org> <20070622204058.GA11777@elte.hu> <20070622215953.GA22917@elte.hu> <1182797325.1689.14.camel@hinata.boston.redhat.com> <20070625211551.GA29390@elte.hu> In-Reply-To: <20070625211551.GA29390@elte.hu> X-Enigmail-Version: 0.94.1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1952 Lines: 41 Ingo Molnar wrote: > regarding workqueues - would it be possible for you to test Steve's > patch and get us performance numbers? Do you have any test with tons of > tasklet activity that would definitely show the performance impact of > workqueues? I can't speak for Kristian, nor do I have test equipment for isochronous applications, but I know that there are people out there which do data acquisition on as many FireWire buses as they can stuff boards into their boxes. There are also FireWire cards with 2 or 4 controllers per board; and each controller can receive or transmit on several channels. Depending on the buffering scheme, there may be one (?) interrupt per channel and isochronopus cycle. Or an interrupt when the buffer is full. Some application programmers use large buffers; others want small buffers. An isochronous cycle is 125us. Asynchronous I/O can even produce much higher interrupt rates. I think IP over 1394 might indeed cause interrupt rates that are moderately higher than 1/125us during normal traffic. SBP-2 ( = 1394 storage) is not as much affected because the bulk of data is transferred without interrupts. So I suppose some eth1394 bandwidth tests with this patch series might make sense... alas I'm short of spare time. (Would be interesting to see whether the old ohci1394 driver is blown to bits with the patch series; it's an old driver with who-knows what assumptions in there.) > Workqueue priority can be set, and your handler should > probably be SCHED_FIFO. Does this cooperate nicely with a SCHED_FIFO thread of a userspace data acquisition program or audio server or the like? -- Stefan Richter -=====-=-=== -==- ==-=- http://arcgraph.de/sr/ - 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/