Re: Using a new perf tool against an older kernel

From: Arun Sharma
Date: Thu Jun 23 2011 - 15:39:10 EST

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 ( 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".

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