Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754331AbZCEJQw (ORCPT ); Thu, 5 Mar 2009 04:16:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752792AbZCEJQi (ORCPT ); Thu, 5 Mar 2009 04:16:38 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:48179 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752679AbZCEJQh (ORCPT ); Thu, 5 Mar 2009 04:16:37 -0500 Date: Thu, 5 Mar 2009 10:16:11 +0100 From: Ingo Molnar To: Frederic Weisbecker Cc: prasad@linux.vnet.ibm.com, Andrew Morton , Linux Kernel Mailing List , Alan Stern , Roland McGrath Subject: Re: [patch 11/11] ftrace plugin for kernel symbol tracing using HW Breakpoint interfaces Message-ID: <20090305091611.GB16026@elte.hu> References: <20090305043440.189041194@linux.vnet.ibm.com> <20090305044333.GM17747@in.ibm.com> <20090305063703.GB5359@nowhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090305063703.GB5359@nowhere> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=none autolearn=no SpamAssassin version=3.2.3 _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1335 Lines: 46 * Frederic Weisbecker wrote: > On Thu, Mar 05, 2009 at 10:13:33AM +0530, prasad@linux.vnet.ibm.com wrote: > > This patch adds an ftrace plugin to detect and profile memory access over > > kernel variables. It uses HW Breakpoint interfaces to 'watch memory > > addresses. > > > > Signed-off-by: K.Prasad > > --- > > > Hi, > > Nice feature. And moreover the standardized hardware > breakpoints could be helpful for tracing. yeah. The feature is much more alive now. > Just some comments below. One other thing: +#ifdef CONFIG_FTRACE_SELFTEST +int trace_selftest_startup_ksym(struct tracer *trace, struct trace_array *tr) +{ + /* TODO: Will be implemented later */ + return 0; +} +#endif /* CONFIG_FTRACE_SELFTEST */ This needs to be implemented before i can pick the code up into tip:tracing, as otherwise we will not notice it fast enough if some of this stuff breaks. Basically the ftrace plugin will be the main usage vector of this facility, so the self-test is a must-have. Looks very nice otherwise. Ingo -- 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/