Re: [PATCH] s390: Add support for z13

On Wed, 5 Oct 2016, Andreas Arnez wrote:
> On Tue, Oct 04 2016, Michael Petlan wrote:
>
>> Hi Andreas,
>>
>> have you or anyone tested this patch and/or s390 oprofile support
>> in general? I'd love to know more about the results or at least,
>> if there any, what has been tested and what not + whether there
>> are any known issues regarding to HW sampling on s390.
>
> IIRC, I just performed a quick smoke test before submitting this patch;
> and oprofile didn't crash.  Other than that, I don't really know what
> works and what doesn't.
>

Could you please try it with setting /proc/sys/kernel/kptr_restrict to '0'
and /proc/sys/kernel/perf_event_paranoid to '-1', being logged as root user?

`ophelp -r`
   --> should detect the machine, print "IBM z13"

`ophelp -d`
   --> should print default event "CPU_CYCLES"

`ocount ls`
   --> should return some non-zero value for event CPU_CYCLES

`ocount -e INSTRUCTIONS ls`
   --> should use INSTRUCTIONS and return a non-zero value too

Please try out also the --system-wide mode as root.

If the above commands work, at least the basic z13 support can be verified.

> Some people mentioned various issues with oprofile on s390, depending on
> kernel version and environment.  Since I'm currently more focused on
> other projects, I haven't investigated them.  Here are some
> (unconfirmed) examples:
>
> * The --help/--usage options of operf and ocount behave strangely.
>  E.g., they attempt perf_open and just emit a cryptic error message if
>  that fails.  And upon success they still yield exit code 1.

Maybe if /proc/sys/kernel/perf_event_paranoid is '2' and the user is not
root, this might happen.

>
> * operf is showing a warning message:
>
>    Kernel profiling is not possible with current system config.
>    Set /proc/sys/kernel/kptr_restrict to 0 to collect kernel samples.
>
Is kptr_restrict set to '0'?

> * Without the --system-wide option, operf generates all-zero statistics.

Does `ocount` do the same? If yes, the event counting probably does not
work as expected.


Thanks!
Michael

>
> --
> Andreas
>
>

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