Messages in this thread | | | Subject | Re: [ANNOUNCE] New utility: 'trace' | From | Peter Zijlstra <> | Date | Wed, 17 Nov 2010 14:10:13 +0100 |
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On Wed, 2010-11-17 at 15:05 +0200, Török Edwin wrote: > On Wed, 17 Nov 2010 13:51:52 +0100 > Peter Zijlstra <peterz@infradead.org> wrote: > > > On Wed, 2010-11-17 at 14:47 +0200, Török Edwin wrote: > > > I see --call-graph in the trace record -h output, but it doesn't > > > seem to work on x86_64 for me. > > > > If you want to unwind userspace you need to build everything with > > framepointers -- sadly some people have been lobbying to remove > > framepointers from all distro builds, even though on x86_64 its nearly > > free (i386 does have a significant performance benefit, sadly). > > > > There's some work on-going to simply copy out the top of stack and let > > dwarves go wild at it in userspace, but that isn't done yet. > > Even without frame-pointers I should see at least the first caller in > userspace, since that can be obtained by reading the return address of > the syscall, right?
Right.
> I don't see any difference in the output of 'trace report' thats why > I'm asking it is implemented at all right now, or I need additional > flags to see it.
Ah, I haven't actually looked at any of the perf-trace code yet, so I'm afraid I can't answer that particular question.
> I do see some difference in output of 'perf record -g/perf report' > though.
ok.
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