From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266739AbUGLGjH (ORCPT ); Mon, 12 Jul 2004 02:39:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266740AbUGLGjH (ORCPT ); Mon, 12 Jul 2004 02:39:07 -0400 Received: from fw.osdl.org ([65.172.181.6]:31455 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S266739AbUGLGjC (ORCPT ); Mon, 12 Jul 2004 02:39:02 -0400 Date: Sun, 11 Jul 2004 23:37:50 -0700 From: Andrew Morton To: Con Kolivas Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] Instrumenting high latency Message-Id: <20040711233750.2050c4b1.akpm@osdl.org> In-Reply-To: References: X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Con Kolivas wrote: > > Because of the recent discussion about latency in the kernel I asked William > Lee Irwin III to help create some instrumentation to determine where in the > kernel there were still sustained periods of non-preemptible code. He hacked > together this simple patch which times periods according to the preempt > count. Looks sane. > The patch appears to require CONFIG_PREEMPT enabled on uniprocessor and is > i386 only at the moment. Not sure what you mean by "on uniprocessor"? AFAICT the patch will work as-is on uniprocessor and on SMP. Looks like it'll work with CONFIG_PREEMPT=n, too, although that would be a slightly bizarre thing to do. + print_symbol("%s\n", + __get_cpu_var(preempt_exit)); I'll change this to print_symbol("%s", __get_cpu_var(preempt_exit)); printk("\n"); so it doesn't make a mess with CONFIG_KALLSYMS=n.