On Mon, 6 Jul 2015 10:56:50 -0300 Arnaldo Carvalho de Melo <[email protected]> wrote:
> Em Mon, Jul 06, 2015 at 04:17:31AM +0000, Wang Nan escreveu: > > This patch allows passing perf's own PID to '--filter' by using > > '@PERFPID'. This should be useful when system-widely capturing > > tracepoints events. > > Steven, does filters have any special meaning for @? Not as of yet. > > > Before this patch, when doing something like: > > > > # perf record -a -e syscalls:sys_enter_write <cmd> > > > > One could easily get result like this: > > > > # /tmp/perf report --stdio > > ... > > # Overhead Command Shared Object Symbol > > # ........ ....... .................. .................... > > # > > 99.99% perf libpthread-2.18.so [.] __write_nocancel > > 0.01% ls libc-2.18.so [.] write > > 0.01% sshd libc-2.18.so [.] write > > ... > > > > Where most events are generated by perf itself. > > > > A shell trick can be done to filter perf itself out: > > > > # cat << EOF > ./tmp > > > #!/bin/sh > > > exec perf record -e ... --filter="common_pid != \$\$" -a sleep 10 > > > EOF > > # chmod a+x ./tmp > > # ./tmp > > > > However, doing so is user unfriendly. > > > > This patch introduces '@PERFPID' placeholder to '--filter' options. Now > > user is allowed to the above work with: > > > > # perf record -e ... --filter="common_pid != @PERFPID' sleep 10 What about using '$' instead. That is more common to shell scripts of being a variable. -- Steve > > > > Signed-off-by: Wang Nan <[email protected]> > > --- > > tools/perf/Documentation/perf-record.txt | 1 + > > <SNIP> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
