Re: Using a new perf tool against an older kernel
From: Frederic Weisbecker
Date: Thu Jun 23 2011 - 20:11:40 EST
On Thu, Jun 23, 2011 at 12:39:54PM -0700, Arun Sharma wrote:
> On 6/23/11 7:22 AM, David Ahern wrote:
> >I have not seen issues like this using newer perf userspace against
> >older kernels. For example, my laptop was running Fedora 14 (2.6.35) and
> >now Fedora 15 (184.108.40.206) and I typically use latest perf builds (e.g.,
> >testing patches).
> I narrowed it down to PERF_SAMPLE_RAW:
> perf record -ag -- sleep 1
> is fine, but:
> perf record -agR -- sleep 1
> fails for me most of the time. The reason I needed to use the -R in
> the first place is that "perf script" fails on older kernels with:
> Samples do not contain timestamps.
> With the newer perf, I don't get errors, but the timestamp field is
> invalid. So I need to use the -R flag to get valid timestamps +
> stacktraces out of "perf script".
I'm confused, you first said it happens with new tools on older kernel.
Can you tell us which combination of kernel/user raises the error? and
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