[CRIU] [PATCH] [RFC] perf: Here is an example how to trace syscalls

[Christopher Covington]

On 09/30/2014 08:05 AM, Andrey Vagin wrote:
> perf doesn't affect performance so significant as strace and
> it allows to trace parasite code.
> 
> All processes are executed in a new perf_evets cgroup and
> "perf record" collects events only for processes from this group.
> 
> Signed-off-by: Andrey Vagin <avagin at openvz.org>
> ---
>  test/zdtm.sh | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/test/zdtm.sh b/test/zdtm.sh
> index b5133c3..1eba6d7 100755
> --- a/test/zdtm.sh
> +++ b/test/zdtm.sh
> @@ -1,5 +1,8 @@
>  #!/bin/bash
>  
> +test -d /sys/fs/cgroup/perf_event/zdtm || mkdir /sys/fs/cgroup/perf_event/zdtm || exit 1
> +echo $$ > /sys/fs/cgroup/perf_event/zdtm/tasks
> +
>  ARCH=`uname -m | sed			\
>  		-e s/i.86/i386/		\
>  		-e s/sun4u/sparc64/	\
> @@ -582,8 +585,14 @@ EOF
>  
>  		save_fds $PID  $ddump/dump.fd
>  		save_maps $PID  $ddump/dump.maps
> -		setsid $CRIU_CPT $dump_cmd -D $ddump -o dump.log -v4 -t $PID $gen_args $cpt_args
> +		echo $$ > /sys/fs/cgroup/perf_event/tasks
> +		perf record -o $ddump/perf.dump -e raw_syscalls:sys_exit,raw_syscalls:sys_enter --cgroup test,test -a bash <<EOF
> +echo 0 > /sys/fs/cgroup/perf_event/zdtm/tasks &&
> +$CRIU_CPT $dump_cmd -D $ddump -o dump.log -v4 -t $PID $gen_args $cpt_args
> +EOF

The man page on Ubuntu 12.04 says -a and --cgroup are incompatible.

-a, --all-cpus
    System-wide collection from all CPUs.

-G name,..., --cgroup name,...
    monitor only in the container (cgroup) called "name". This option is
    available only in per-cpu mode.

Why do you need container based monitoring instead of just command-and-childen
based with `perf record $CRIU_CPT`?

Christopher

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