| Date | Wed, 11 Dec 2013 14:49:52 -0700 | From | David Ahern <> | Subject | Re: [PATCH v0 13/71] perf tools: Add machine__get_thread_pid() |
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On 12/11/13, 2:18 PM, Andi Kleen wrote: > David Ahern <dsahern@gmail.com> writes: >> >> Are you looking up the current or next task? If the former why not use >> sample->pid rather than parsing the sched_switch tracepoint? > > The itrace stream doesn't have a pid field, and it needs the exact > time stamp of the switch. There may not actually be any samples > before decoding. > > -Andi >
What I meant is this:
perf record -e sched:sched_switch -a -- sleep 1 | perf script -f comm,tid,pid,event,trace
qemu-system-x86 8688/8692 sched:sched_switch: prev_comm=qemu-system-x86 prev_pid=8692 prev_prio=120 prev_state=S ==> next_comm=swapper/15 next_pid=0 next_prio=120
8688/8692 are the pid and tid of the running task. If you are monitoring sched_switch events and looking at running task -- the one getting scheduled out -- you don't need to parse the tracepoint. But, if you want to know next task then you do need to parse it. I was wondering which task is getting looked up.
David
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