Messages in this thread | | | Date | Tue, 05 May 2015 16:24:54 -0600 | From | David Ahern <> | Subject | Re: [Question] How does perf still record the stack of a specified pid even when that process is interrupted and CPU is scheduled to other process |
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On 5/5/15 3:53 PM, Rabin Vincent wrote: > The commands above will identify the sys_write which takes time but only > provide the stacktrace at the entry and exit of the syscall, but this do > not show why the process blocked or what it did inside the system call. > > So a way to get what is required for the use case would be to make the > following changes to the above sequence: > > (1) include the sched:* events when perf trace record is run > > (2) around the time of interest, look at the kernel stack st the sched:switch > events between the entry and the exit. This will show what the process was > waiting for when it when it blocked. The stacktraces at the > stat_runtime events in the process may also be useful to understand what > was going on.
agreed.
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