Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752570Ab0AUNUX (ORCPT ); Thu, 21 Jan 2010 08:20:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752164Ab0AUNUX (ORCPT ); Thu, 21 Jan 2010 08:20:23 -0500 Received: from mail-fx0-f220.google.com ([209.85.220.220]:58414 "EHLO mail-fx0-f220.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752053Ab0AUNUW (ORCPT ); Thu, 21 Jan 2010 08:20:22 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=ebd12Rg2akQG9aQmnRWKUgx6app13hy5eSBM7pVshR+JXAcqYtl/oEZKX84AMTBZAN M7GiaN7PmoaPDjQoKIN9anKQdgIJeusCe7034FiP+WV6ixQZ947+6IQ1TlE4Bkj6PfI5 Gn73UimW9pr3S8Kjs/53wUEFzXz3iPOjdE5gc= Date: Thu, 21 Jan 2010 14:20:18 +0100 From: Frederic Weisbecker To: Anton Blanchard Cc: Peter Zijlstra , Paul Mackerras , Ingo Molnar , Benjamin Herrenschmidt , Paul Mundt , linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf: Fix inconsistency between IP and callchain sampling Message-ID: <20100121132014.GH5017@nowhere> References: <20100118054707.GT12666@kryten> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100118054707.GT12666@kryten> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1383 Lines: 32 On Mon, Jan 18, 2010 at 04:47:07PM +1100, Anton Blanchard wrote: > > When running perf across all cpus with backtracing (-a -g), sometimes we > get samples without associated backtraces: > > 23.44% init [kernel] [k] restore > 11.46% init eeba0c [k] 0x00000000eeba0c > 6.77% swapper [kernel] [k] .perf_ctx_adjust_freq > 5.73% init [kernel] [k] .__trace_hcall_entry > 4.69% perf libc-2.9.so [.] 0x0000000006bb8c > | > |--11.11%-- 0xfffa941bbbc > > It turns out the backtrace code has a check for the idle task and the IP > sampling does not. This creates problems when profiling an interrupt > heavy workload (in my case 10Gbit ethernet) since we get no backtraces > for interrupts received while idle (ie most of the workload). > > Right now x86 and sh check that current is not NULL, which should never > happen so remove that too. > > Signed-off-by: Anton Blanchard I'm queuing it. Thanks. -- 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/