Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751488Ab0HOWyB (ORCPT ); Sun, 15 Aug 2010 18:54:01 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:56454 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751060Ab0HOWyA (ORCPT ); Sun, 15 Aug 2010 18:54:00 -0400 Date: Sun, 15 Aug 2010 18:53:59 -0400 From: Christoph Hellwig To: acme@redhat.com Cc: linux-kernel@vger.kernel.org Subject: callchain sampling bug in perf? Message-ID: <20100815225359.GA32152@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-08-17) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1493 Lines: 34 I'm trying to play with perf record -g, that is sampling the callchains. Doing this with simple workloads works fine, but when I try to do this with compilebench a lot of samples seem to get lost. I'm doing the following: perf probe --add xlog_sync perf record -g -e probe:xlog_sync -- ./compilebench Trying to report it I do not get any callchains at all: [root@virtlab106 compilebench-0.6]# perf report -g flat -n # Events: 9K cycles # # Overhead Samples Command Shared Object Symbol # ........ .......... ............ ................. ......... # 70.41% 6757 compilebench [kernel.kallsyms] [k] xlog_sync 22.61% 2170 sync [kernel.kallsyms] [k] xlog_sync 3.89% 373 sh [kernel.kallsyms] [k] xlog_sync 2.50% 240 python [kernel.kallsyms] [k] xlog_sync 0.33% 32 :3881 [kernel.kallsyms] [k] xlog_sync 0.13% 12 :3971 [kernel.kallsyms] [k] xlog_sync 0.11% 11 :3956 [kernel.kallsyms] [k] xlog_sync 0.01% 1 :3972 [kernel.kallsyms] [k] xlog_sync Doing a perf report -g flat,0.0 -n shows lots of callgraph, but the percentag for them doesn't add up at all. -- 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/