Re: Getting started with perf; a couple of questions

[David Ahern <dsahern@gmail.com>]

On 6/7/13 5:49 PM, Andrew Davidoff wrote:

> You are correct that the Ubuntu 10.04 host that doesn't seem to be
> recording properly is running a 2.6.32 kernel (2.6.32-47-server from
> Ubuntu). The invocation of perf record is the same as described for
> the CentOS VM (i.e. I am not using -p, and would like to not use -a,
> though -a is the only way I'm getting samples recorded for
> <command-to-trace>).

CentOS 6 has newer perf code than its kernel version suggests -- 
compliments of the RHEL backporting Jiri does.

>
> I had moved to building a newer version of perf than the one that came
> from the Ubuntu 10.04 repo (linux-tools-common) because that one
> appeared ancient based on the output it was generating, and reports
> version as 0.0.2.PERF (though the binary is installed as
> /usr/bin/perf_2.6.32-47). perf record does record data with that
> version, but it looks like (via perf report) that it's data only for
> one event even when multiple are passed, and that event isn't labeled
> in the report, so at a glance I am not sure which it is.

If the original perf command works but newer versions do not then the 
compatibility wheels have fallen off somewhere along the line.

Most likely CentOS 6 works b/c of the backports.

David

>
> Anyway, for now I'm not worrying about getting this working on this
> particular version of Ubuntu, but I appreciate all your help. If I
> decide to dig further I'll start iterating through the versions you
> suggested and see where things get extra broken.
>
> Andy
>