Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755227AbbKRJAc (ORCPT ); Wed, 18 Nov 2015 04:00:32 -0500 Received: from szxga03-in.huawei.com ([119.145.14.66]:4829 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933035AbbKRJAA (ORCPT ); Wed, 18 Nov 2015 04:00:00 -0500 Message-ID: <564C3A0E.3030502@huawei.com> Date: Wed, 18 Nov 2015 16:42:54 +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: Ingo Molnar CC: Jiri Olsa , Arnaldo Carvalho de Melo , David Ahern , Peter Zijlstra , 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> <564C3011.8090002@huawei.com> <20151118082033.GA24726@gmail.com> In-Reply-To: <20151118082033.GA24726@gmail.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=0001.0A020203.564C3E01.010E,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: dccfd85670d8b02c78d12b80bd191b0b Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2971 Lines: 105 On 2015/11/18 16:20, Ingo Molnar wrote: > * Wangnan (F) wrote: > >> On 2015/11/18 15:20, Wangnan (F) wrote: >>> Hi all, >>> >>> When analysising Jiri's patchset [1] I found a dwarf unwind problem. >>> On x86 platform, when sample is at a 'callq' instruction, dwarf based >>> stack unwind always fail. >>> >>> I compile a small C source file with debug information, turn off >>> frame pointer and disable optimization: >>> >>> $ gcc -g -O0 -fomit-frame-pointer ./test_dwarf_unwind.c -o >>> ./test_dwarf_unwind >> For whom want to test it: here is the test code I used. >> >> #include >> #include >> #include >> >> static volatile int x = 0; >> >> int funcc(void) >> { >> struct timeval tv1, tv2; >> unsigned long us1, us2; >> >> gettimeofday(&tv1, NULL); >> >> us1 = tv1.tv_sec * 1000000 + tv1.tv_usec; >> >> while(1) { >> x = x + 100; >> gettimeofday(&tv2, NULL); >> us2 = tv2.tv_sec * 1000000 + tv2.tv_usec; >> if (us2 - us1 >= 3000000) >> break; >> } >> return x; >> } >> int funcb(void) { return funcc();} >> int funca(void) { return funcb();} >> int main() { funca(); return 0;} > What CPU model is this, and what event was used - PEBS perhaps? This might be some > sort of PMU sampling bug/quirk/misfeature - or perhaps a kernel side fixup that > went bad? $ cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 60 model name : Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz stepping : 3 microcode : 0x1c cpu MHz : 3600.000 cache size : 8192 KB physical id : 0 siblings : 8 core id : 0 cpu cores : 4 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm ida arat epb pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt bugs : bogomips : 7183.88 clflush size : 64 cache_alignment : 64 address sizes : 39 bits physical, 48 bits virtual power management: perf cmdline is # ./pref record -g -F 9 --call-graph dwarf ./test_dwarf_unwind Use default events, precise_ip == 2 so uses PEBS. Thank you. > > Thanks, > > 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/