On 5/1/2018 12:33 PM, Jiri Olsa wrote:
On Tue, May 01, 2018 at 07:31:36AM -0700, [email protected] wrote:
From: Kan Liang <[email protected]>
Perf stat doesn't count the uncore event aliases from the same uncore
block in a group, for example:
perf stat -e '{unc_m_cas_count.all,unc_m_clockticks}' -a -I 1000
# time counts unit events
1.000447342 <not counted> unc_m_cas_count.all
1.000447342 <not counted> unc_m_clockticks
2.000740654 <not counted> unc_m_cas_count.all
2.000740654 <not counted> unc_m_clockticks
The output is very misleading. It gives a wrong impression that the
uncore event doesn't work.
An uncore block could be composed by several PMUs. An uncore event alias
is a joint name which means the same event runs on all PMUs of a block.
Perf doesn't support mixed events from different PMUs in the same group.
It is wrong to put uncore event aliases in a big group.
The right way is to split the big group into multiple small groups which
only include the events from the same PMU.
Only uncore event aliases from the same uncore block should be specially
handled here. It doesn't make sense to mix the uncore events with other
uncore events from different blocks or even core events in a group.
With the patch:
# time counts unit events
1.001557653 140,833 unc_m_cas_count.all
1.001557653 1,330,231,332 unc_m_clockticks
2.002709483 85,007 unc_m_cas_count.all
2.002709483 1,429,494,563 unc_m_clockticks
Reported-by: Andi Kleen <[email protected]>
Signed-off-by: Kan Liang <[email protected]>
---
Changes since V4:
- Add WARN_ON when failing to alloc an array for leaders
- Add comments to explain why it has to go through the whole group
Acked-by: Jiri Olsa <[email protected]>
Thanks Jirka.
Hi Arnaldo,
Are you OK with the patch?
It looks like Jirka has another patch which will touch the same code.
If it's OK for you, could you please merge the patch? So he can do the
changes on top of this patch.
Thanks,
Kan
