linux-kernel - Re: [PATCH V2 09/13] perf script: show kernel overhead

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Date:   Sun, 4 Dec 2016 22:25:48 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     kan.liang@...el.com
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        linux-kernel@...r.kernel.org, alexander.shishkin@...ux.intel.com,
        tglx@...utronix.de, namhyung@...nel.org, jolsa@...nel.org,
        adrian.hunter@...el.com, wangnan0@...wei.com, mark.rutland@....com,
        andi@...stfloor.org
Subject: Re: [PATCH V2 09/13] perf script: show kernel overhead

On Fri, Dec 02, 2016 at 04:19:17PM -0500, kan.liang@...el.com wrote:
> From: Kan Liang <kan.liang@...el.com>
> 
> Shows kernel overhead in perf script.
> 
> The output is as below:
> 
> perf script --show-profiling-cost-events
>             perf 29001 79989.093958:          1 cycles:
> ffffffff81064ca6 native_write_msr (/lib/
>            sleep 29001 79989.094282:       7661 cycles:
> ffffffff810dc433 update_blocked_averages
>            sleep 29001 79989.094294:       7442 cycles:
> ffffffff81810f60 irq_work_interrupt (/li
>            sleep 29001 79989.094305:      25466 cycles:
> ffffffff813ca410 radix_tree_next_chunk (
>            sleep 29001 79989.094340:      94368 cycles:
> ffffffff8180fa90 page_fault (/lib/module
>            sleep 29001 79989.094459:     167362 cycles:
> ffffffff811e3f79 alloc_set_pte (/lib/mod
>            sleep 29001 79989.094672:     190283 cycles:
> 7f5d7c91d8e7 _dl_addr (/usr/lib64/li
>            sleep 29001 79991.094978:     194526 cycles:
> ffffffff811e0579 __tlb_remove_page_size.
>            sleep 29001 79991.095061: PERF_RECORD_OVERHEAD [SAMPLE] nr: 8
> time: 28110
>            sleep 29001 79991.095062: PERF_RECORD_OVERHEAD [SB] nr: 24
> time: 41397

hi,
got segfault by running:

[jolsa@...-x3650m4-01 perf]$ catchsegv ./perf --no-pager script --show-profiling-cost-events

Backtrace:
/home/jolsa/linux-perf/tools/perf/builtin-script.c:1281(process_overhead_event)[0x4351c4]
/home/jolsa/linux-perf/tools/perf/util/session.c:1399(perf_session__process_user_event)[0x4e997b]
/home/jolsa/linux-perf/tools/perf/util/session.c:1501(perf_session__process_event)[0x4e9de3]
/home/jolsa/linux-perf/tools/perf/util/session.c:1918 (discriminator 1)(__perf_session__process_events)[0x4eae1b]
/home/jolsa/linux-perf/tools/perf/util/session.c:1972(perf_session__process_events)[0x4eb019]
/home/jolsa/linux-perf/tools/perf/builtin-script.c:1321(__cmd_script)[0x43538c]
/home/jolsa/linux-perf/tools/perf/builtin-script.c:2498(cmd_script)[0x438f8e]
/home/jolsa/linux-perf/tools/perf/perf.c:358(run_builtin)[0x495452]
/home/jolsa/linux-perf/tools/perf/perf.c:420(handle_internal_command)[0x4956bf]
/home/jolsa/linux-perf/tools/perf/perf.c:469(run_argv)[0x495804]
/home/jolsa/linux-perf/tools/perf/perf.c:610(main)[0x495bed]
/lib64/libc.so.6(__libc_start_main+0xf1)[0x7f5932390401]
??:?(_start)[0x40a80a]
??:0(??)[0x0]


jirka