Re: [tip:perfcounters/core] perf trace: Sample the CPU too

Frederic Weisbecker
2009-09-02T21:44:56Z

On Wed, Sep 02, 2009 at 07:31:51PM +0000, tip-bot for Ingo Molnar wrote:
> Commit-ID: cd6feeeafddbef6abfe4d90fb26e42fd844d34ed
> Gitweb: http://git.kernel.org/tip/cd6feeeafddbef6abfe4d90fb26e42fd844d34ed
> Author: Ingo Molnar <mingo@elte.hu>
> AuthorDate: Wed, 2 Sep 2009 20:20:38 +0200
> Committer: Ingo Molnar <mingo@elte.hu>
> CommitDate: Wed, 2 Sep 2009 21:28:50 +0200
>
> perf trace: Sample the CPU too
>
> Sample, record, parse and print the CPU field - it had all zeroes before.
>
> Before (watch the second column, the CPU values):
>
> perf-32685 [000] 0.000000: sched_wakeup_new: task perf:32686 [120] success=1 [011]
> perf-32685 [000] 0.000000: sched_migrate_task: task perf:32685 [120] from: 1 to: 11
> perf-32685 [000] 0.000000: sched_process_fork: parent perf:32685 child perf:32686
> true-32686 [000] 0.000000: sched_wakeup: task migration/11:25 [0] success=1 [011]
> true-32686 [000] 0.000000: sched_wakeup: task distccd:12793 [125] success=1 [015]
> true-32686 [000] 0.000000: sched_wakeup: task distccd:12793 [125] success=1 [015]
> perf-32685 [000] 0.000000: sched_switch: task perf:32685 [120] (S) ==> swapper:0 [140]
> true-32686 [000] 0.000000: sched_switch: task perf:32686 [120] (R) ==> migration/11:25 [0]
> true-32686 [000] 0.000000: sched_switch: task perf:32686 [120] (R) ==> distccd:12793 [125]
> true-32686 [000] 0.000000: sched_switch: task true:32686 [120] (R) ==> distccd:12793 [125]
> true-32686 [000] 0.000000: sched_process_exit: task true:32686 [120]
> true-32686 [000] 0.000000: sched_stat_wait: task: distccd:12793 wait: 6767985949080 [ns]
> true-32686 [000] 0.000000: sched_stat_wait: task: distccd:12793 wait: 6767986139446 [ns]
> true-32686 [000] 0.000000: sched_stat_sleep: task: distccd:12793 sleep: 132844 [ns]
> true-32686 [000] 0.000000: sched_stat_sleep: task: distccd:12793 sleep: 131724 [ns]
>
> After:
>
> perf-32685 [001] 0.000000: sched_wakeup_new: task perf:32686 [120] success=1 [011]
> perf-32685 [001] 0.000000: sched_migrate_task: task perf:32685 [120] from: 1 to: 11
> perf-32685 [001] 0.000000: sched_process_fork: parent perf:32685 child perf:32686
> true-32686 [011] 0.000000: sched_wakeup: task migration/11:25 [0] success=1 [011]
> true-32686 [015] 0.000000: sched_wakeup: task distccd:12793 [125] success=1 [015]
> true-32686 [015] 0.000000: sched_wakeup: task distccd:12793 [125] success=1 [015]
> perf-32685 [001] 0.000000: sched_switch: task perf:32685 [120] (S) ==> swapper:0 [140]
> true-32686 [011] 0.000000: sched_switch: task perf:32686 [120] (R) ==> migration/11:25 [0]
> true-32686 [015] 0.000000: sched_switch: task perf:32686 [120] (R) ==> distccd:12793 [125]
> true-32686 [015] 0.000000: sched_switch: task true:32686 [120] (R) ==> distccd:12793 [125]
> true-32686 [015] 0.000000: sched_process_exit: task true:32686 [120]
> true-32686 [015] 0.000000: sched_stat_wait: task: distccd:12793 wait: 6767985949080 [ns]
> true-32686 [015] 0.000000: sched_stat_wait: task: distccd:12793 wait: 6767986139446 [ns]
> true-32686 [015] 0.000000: sched_stat_sleep: task: distccd:12793 sleep: 132844 [ns]
> true-32686 [015] 0.000000: sched_stat_sleep: task: distccd:12793 sleep: 131724 [ns]
>
> So we can now see how this workload migrated between CPUs.
>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> LKML-Reference: <new-submission>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
>
>
> ---
> tools/perf/builtin-record.c | 4 +++-
> tools/perf/builtin-trace.c | 9 ++++++++-
> 2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index add514d..ff93f8e 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -403,8 +403,10 @@ static void create_counter(int counter, int cpu, pid_t pid)
> if (call_graph)
> attr->sample_type |= PERF_SAMPLE_CALLCHAIN;
>
> - if (raw_samples)
> + if (raw_samples) {
> attr->sample_type |= PERF_SAMPLE_RAW;
> + attr->sample_type |= PERF_SAMPLE_CPU;
> + }
>
> attr->mmap = track;
> attr->comm = track;
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index 8247fd0..bbe4c44 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -58,12 +58,19 @@ process_sample_event(event_t *event, unsigned long offset, unsigned long head)
> struct dso *dso = NULL;
> struct thread *thread;
> u64 ip = event->ip.ip;
> + u32 cpu = -1;
> u64 period = 1;
> void *more_data = event->ip.__more_data;
> int cpumode;
>
> thread = threads__findnew(event->ip.pid, &threads, &last_match);
>
> + if (sample_type & PERF_SAMPLE_CPU) {
> + cpu = *(u32 *)more_data;
> + more_data += sizeof(u32);
> + more_data += sizeof(u32); /* reserved */
> + }
> +

Cool, I've searched an easy way to have the cpu and I wasn't even aware of
this type of event :-)

What about the timestamp now? I guess a specific field should be filled
for tracepoint raw samples.
Or may be for every raw samples?

> if (sample_type & PERF_SAMPLE_PERIOD) {
> period = *(u64 *)more_data;
> more_data += sizeof(u64);
> @@ -120,7 +127,7 @@ process_sample_event(event_t *event, unsigned long offset, unsigned long head)
> * field, although it should be the same than this perf
> * event pid
> */
> - print_event(0, raw->data, raw->size, 0, thread->comm);
> + print_event(cpu, raw->data, raw->size, 0, thread->comm);
> }
> total += period;
>