Em Mon, Jan 14, 2013 at 03:14:02PM +0100, Stephane Eranian escreveu: > 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
But you have to due to the problem you noticed below. > to measure the processes I own. So the error message is confusing > here. indeed > 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. Right, I need to resume working on properly fixing this, I got sidetracked when I got the same point as you in the above analysis :-\ Will try to recover the conversations I had about this. - Arnaldo -- 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/
