Messages in this thread |  | | Subject | Re: [PATCH] perf stat: Skip duration_time in setup_system_wide | From | "Jin, Yao" <> | Date | Wed, 23 Sep 2020 10:05:56 +0800 |
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Hi Arnaldo,
On 9/23/2020 2:02 AM, Arnaldo Carvalho de Melo wrote: > Em Tue, Sep 22, 2020 at 02:56:30PM -0300, Arnaldo Carvalho de Melo escreveu: >> Em Tue, Sep 22, 2020 at 09:50:04AM +0800, Jin Yao escreveu: >>> Some metrics (such as DRAM_BW_Use) consists of uncore events and >>> duration_time. For uncore events, counter->core.system_wide is >>> true. But for duration_time, counter->core.system_wide is false >>> so target.system_wide is set to false. >>> >>> Then 'enable_on_exec' is set in perf_event_attr of uncore event. >>> Kernel will return error when trying to open the uncore event. >>> >>> This patch skips the duration_time in setup_system_wide then >>> target.system_wide will be set to true for the evlist of uncore >>> events + duration_time. >>> >>> Before (tested on skylake desktop): >>> >>> # perf stat -M DRAM_BW_Use -- sleep 1 >>> Error: >>> The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (arb/event=0x84,umask=0x1/). >>> /bin/dmesg | grep -i perf may provide additional information. >>> >>> After: >>> >>> # perf stat -M DRAM_BW_Use -- sleep 1 >>> >>> Performance counter stats for 'system wide': >>> >>> 169 arb/event=0x84,umask=0x1/ # 0.00 DRAM_BW_Use >>> 40,427 arb/event=0x81,umask=0x1/ >>> 1,000,902,197 ns duration_time >>> >>> 1.000902197 seconds time elapsed >>> >>> Fixes: 648b5af3f3ae ("libperf: Move 'system_wide' from 'struct evsel' to 'struct perf_evsel'") >> >> Humm, what makes you think that this cset was the one introducing this >> problem? It just moves evsel->system_wide to evsel->core.system_wide. > > Apart from that I reproduced the problem and after applying your patch > it seems cured: > > [acme@quaco perf]$ grep 'model name' -m1 /proc/cpuinfo > model name : Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz > > Before (with -v to see details): > > [root@quaco ~]# perf stat -v -M DRAM_BW_Use -- sleep 1 > Using CPUID GenuineIntel-6-8E-A > metric expr 64 * ( arb@event\=0x81\,umask\=0x1@ + arb@event\=0x84\,umask\=0x1@ ) / 1000000 / duration_time / 1000 for DRAM_BW_Use > found event duration_time > found event arb/event=0x84,umask=0x1/ > found event arb/event=0x81,umask=0x1/ > adding {arb/event=0x84,umask=0x1/,arb/event=0x81,umask=0x1/}:W,duration_time > Control descriptor is not initialized > Warning: > arb/event=0x84,umask=0x1/ event is not supported by the kernel. > Error: > The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (arb/event=0x84,umask=0x1/). > /bin/dmesg | grep -i perf may provide additional information. > > [root@quaco ~]# > > After: > > [root@quaco ~]# perf stat -M DRAM_BW_Use -- sleep 1 > > Performance counter stats for 'system wide': > > 2,806 arb/event=0x84,umask=0x1/ # 0.63 DRAM_BW_Use > 10,001,820 arb/event=0x81,umask=0x1/ > 1,016,875,686 ns duration_time > > 1.016875686 seconds time elapsed > > [root@quaco ~]# > > So I'm removing that fixes and adding this one, that I think is where > "duration_time" was being considered... > > Fixes: e3ba76deef23064f ("perf tools: Force uncore events to system wide monitoring") >
Yes, this fixes is much better, thanks.
> Also, wouldn't it be better to have the duration_time event with its > evsel->core.system_wide set to true? >
That looks to be another solution, should be OK too I think. :)
But anyway we need a test.
Thanks Jin Yao
> - Arnaldo >
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