Hi, On Tue, Jul 7, 2015 at 12:38 PM, Wang Nan <wangn...@huawei.com> wrote: > This patch allows passing perf's own PID to '--filter' by using > '$PERFPID'. This should be useful when system-widely capturing > tracepoints events. > > Before this patch, when doing something like: > > # perf record -a -e syscalls:sys_enter_write <cmd> > > One could easily get result like this: > > # perf report --stdio > ... > # Overhead Command Shared Object Symbol > # ........ ....... .................. .................... > # > 99.99% perf libpthread-2.18.so [.] __write_nocancel > 0.01% ls libc-2.18.so [.] write > 0.01% sshd libc-2.18.so [.] write > ... > > Where most events are generated by perf itself. > > A shell trick can be done to filter perf itself out: > > # cat << EOF > ./tmp > > #!/bin/sh > > exec perf record -e ... --filter="common_pid != \$\$" -a sleep 10 > > EOF > # chmod a+x ./tmp > # ./tmp > > However, doing so is user unfriendly. > > This patch introduces '$PERFPID' placeholder to perf's filter. Now > user is allowed to do the above work with: > > # perf record -e ... --filter='common_pid != $PERFPID' -a sleep 10
Instead, what about adding an option to do the same thing, like --exclude-perf or something? Thanks, Namhyung > > This patch adds the variable replacement code to perf_evsel__apply_filter(), > before PERF_EVENT_IOC_SET_FILTER ioctl, so not only 'perf record', all > subcommands which uses filter can utilize $PERFPID. > > Andi Kleen sent a similar patch at 2014, but wasn't applied, the > reason is not clear. > > Signed-off-by: Wang Nan <wangn...@huawei.com> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
