Hi, I was trying to use the --uid option of perf record but it fails for me no matter what I tried. Looks like the goal of this option is to measure ALL the processes owned by the specified uid. Each process is measured in per-thread mode.
However for me it failed on all my attempts when running with 3.8.0-rc3 on Ubuntu Quantal. $ perf record --uid=eranian sleep 4 Error: Permission error - are you root? Consider tweaking /proc/sys/kernel/perf_event_paranoid: -1 - Not paranoid at all 0 - Disallow raw tracepoint access for unpriv 1 - Disallow cpu events for unpriv 2 - Disallow kernel profiling for unpriv sleep: Terminated You don't want to be root to run this command. Should not require to measure the processes I own. So the error message is confusing here. After some debugging, I came to the conclusion that this command fails when it hits the sshd daemon: eranian 2439 0.0 0.0 110424 1968 ? S 15:07 0:00 sshd: eranian@pts/2 root 2301 0.0 0.0 110424 4420 ? Ss 15:07 0:00 sshd: eranian [priv] I mean the sshd process owned by me. It is owned by me but I cannot attached an event to it. I get EACCES and I suspect it's because of missing ptrace privilege. The sshd binary is obviously not setuid. So there is something else preventing ptrace. In fact, even strace -p 2349 fails. Looked online and there were a couple of mentions to the Yama security model and the ptrace_scope sysctl control. I tried that and it did not help. So looks to me that something is broken somewhere. If the kernel restrictions are normal, then I think perf record should warn that it has to skip the sshd process and continue with the other processes owned by me. That seems more useful than the current situation. But I may be missing something here. If so please explain to me. Thanks. -- 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/
