Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755428AbbKRJL5 (ORCPT ); Wed, 18 Nov 2015 04:11:57 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:48313 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755375AbbKRJLm (ORCPT ); Wed, 18 Nov 2015 04:11:42 -0500 Message-ID: <564C3EB1.5030609@huawei.com> Date: Wed, 18 Nov 2015 17:02:41 +0800 From: "Wangnan (F)" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Jiri Olsa CC: Jiri Olsa , Arnaldo Carvalho de Melo , David Ahern , Peter Zijlstra , Ingo Molnar , Milian Wolff , , pi3orama , lizefan 00213767 Subject: Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling taken at 'callq' instruction References: <564C26C4.2040603@huawei.com> <20151118084842.GA10182@krava.brq.redhat.com> In-Reply-To: <20151118084842.GA10182@krava.brq.redhat.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.111.66.109] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020203.564C3FC4.00F6,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 24490190417df135d703d58f4e3d4694 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2082 Lines: 69 On 2015/11/18 16:48, Jiri Olsa wrote: > On Wed, Nov 18, 2015 at 03:20:36PM +0800, Wangnan (F) wrote: > > SNIP > >> Then use perf to trace it: >> >> # ./pref record -g -F 9 --call-graph dwarf ./test_dwarf_unwind >> # ./perf report --no-children --stdio >> ... >> 1.23% test_dwarf_unwi test_dwarf_unwind [.] funcc >> | >> ---funcc >> | >> |--0.62%-- funcb >> | funca >> | main >> | __libc_start_main >> | _start >> | >> --0.62%-- 0 <-- I applied Jiri's patch in [1] so see this >> 0, >> which indicates a broken call chain. > can't see this case after multiple running your test, > just the 'end-of-the-callchain' zeros > > 49.14% test_dwarf_unwi [vdso] [.] __vdso_gettimeofday > | > ---__vdso_gettimeofday > funcc > funcb > funca > main > __libc_start_main > _start > 0 > > 40.78% test_dwarf_unwi [vdso] [.] 0x0000000000000987 > | > ---0x7ffe28ab7987 > __vdso_gettimeofday > funcc > funcb > funca > main > __libc_start_main > _start > 0 > > > what kernel do you have? My kernel is 4.3-rc4. Please see my reply to Ingo. It is possible a problem related to hardware and PEBS? Maybe on your system perf never capture samples on 'callq'? I tested 'cycle' and 'cycle:p', can't get such samples. Only 'cycles:pp' (the default event) have this problem. Thank you. -- 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/