Messages in this thread | | | From | Namhyung Kim <> | Subject | Re: [PATCH 07/13] perf evlist: Fix creation of cpu map | Date | Fri, 04 May 2012 13:05:48 +0900 |
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Hi,
On Wed, 2 May 2012 15:40:33 -0300, Arnaldo Carvalho de Melo wrote: > Em Fri, Apr 27, 2012 at 09:16:18AM +0900, Namhyung Kim escreveu: >> So as long as you set perf_event_paranoid to -1 or run perf test as >> root, you cannot see the failure. > > Ok, as root try 'perf top', here I get, with this patch: > > [root@sandy ~]# perf top --stdio > Warning: > The sys_perf_event_open() syscall returned with 22 (Invalid argument). > /bin/dmesg may provide additional information. > No CONFIG_PERF_EVENTS=y kernel support configured? > [root@sandy ~]# > > Skipping this one, will look again later. > > - Arnaldo
Sorry. It is because perf top depends on an undefined behaviour that if neither target nor command line argument was specified it'd open events for all online cpus. In contrast, perf record and perf stat will show the help message in this case.
This patch makes it clear that we have to prepare a sane target configuration before opening a perf event fd. So I think we should fix perf top to set top.target.system_wide to true by default.
Thanks, Namhyung
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