Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 15 Jan 2002 12:39:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 15 Jan 2002 12:39:28 -0500 Received: from [66.89.142.2] ([66.89.142.2]:60462 "EHLO starship.berlin") by vger.kernel.org with ESMTP id ; Tue, 15 Jan 2002 12:39:14 -0500 Content-Type: text/plain; charset=US-ASCII From: Daniel Phillips To: Robert Love , linux-kernel@vger.kernel.org Subject: Re: [PATCH] update: preemptive kernel for O(1) sched Date: Tue, 15 Jan 2002 15:58:11 +0100 X-Mailer: KMail [version 1.3.2] Cc: kpreempt-tech@lists.sourceforge.net In-Reply-To: <1010961108.814.12.camel@phantasy> <1010982884.1527.52.camel@phantasy> In-Reply-To: <1010982884.1527.52.camel@phantasy> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Message-Id: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On January 14, 2002 05:34 am, Robert Love wrote: > A version of preempt-stats for the 2.5 series kernel is available at: > > ftp://ftp.kernel.org/pub/linux/kernel/people/rml/preempt-stats > > and your favorite mirror. Patches for 2.4 are available, too. > > This patch, used on top of preempt-kernel, allows the measuring of > periods of non-preemptible so that we can identify long-held locks. The > patch creates a proc entry, latencytimes, which contains the top 20 > worst-case recorded periods since it was last read. To begin recording, > read the file once. Subsequent reads will return the results. I.e., Nice, but you need a way to turn it off, for example: echo >/proc/latencytimes i.e., truncate. > [23:25:08]rml@langston:~$ cat /proc/latencytimes > Worst 20 latency times of 277 measured in this period. > usec cause mask start line/file address end line/file > 9982 spin_lock 0 488/sched.c c0117ee2 645/irq.c > 968 BKL 0 666/tty_io.c c0193d58 645/irq.c > 430 spin_lock 0 69/i387.c c010f34f 96/mmx.c > 103 ide0 0 583/irq.c c010ab1c 645/irq.c > 100 BKL 0 2562/buffer.c c014abda 2565/buffer.c > 54 BKL 0 702/tty_io.c c019406b 704/tty_io.c > ... etc A more typical form for the file/line would be, e.g., irq.c:645 > The goal would be to identity the problem areas and fix them. Yep, sorry about the nits but that's the way we nitbots are programmed. -- Daniel - 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/