perf tool: perf mem not working on s390x

perf tool: perf mem not working on s390x

[Thomas-Mich Richter]

When I run perf mem ... it fails with

[root@s8360046 perf]# ./perf mem record -- sleep 1
failed: memory events not supported
[root@s8360046 perf]

That is currently not working on s390.
When I look into the code, the perf mem command is looking for sysfs files in

-r--r--r-- 1 root root 4096 Jun  9 11:02 /sys/devices/cpu/events/mem-loads
-r--r--r-- 1 root root 4096 Jun  9 11:02 /sys/devices/cpu/events/mem-stores

Those 2 sysfs files do not exist on a s390. In fact there is a different
subdirectory tree.

I am not sure how this is handled on the s390 at all. I would have expected
perf mem to somehow retrieve the event numbers and then feed perf record
with these event numbers.
Any comments/ideas on how to handle this?
-- 
Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany
--
Vorsitzende des Aufsichtsrats: Martina Koederitz 
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294

Re: perf tool: perf mem not working on s390x

[Arnaldo Carvalho de Melo]

Em Fri, Jun 23, 2017 at 09:28:53AM +0200, Thomas-Mich Richter escreveu:
> 
> When I run perf mem ... it fails with
> 
> [root@s8360046 perf]# ./perf mem record -- sleep 1
> failed: memory events not supported
> [root@s8360046 perf]
> 
> That is currently not working on s390.
> When I look into the code, the perf mem command is looking for sysfs files in
> 
> -r--r--r-- 1 root root 4096 Jun  9 11:02 /sys/devices/cpu/events/mem-loads
> -r--r--r-- 1 root root 4096 Jun  9 11:02 /sys/devices/cpu/events/mem-stores
> 
> Those 2 sysfs files do not exist on a s390. In fact there is a different
> subdirectory tree.
> 
> I am not sure how this is handled on the s390 at all. I would have expected
> perf mem to somehow retrieve the event numbers and then feed perf record
> with these event numbers.
> Any comments/ideas on how to handle this?

Humm, IIRC perf mem depends on features present only on x86_64, i.e.
mem access features in x86's latest PEBS.

One would have to look for something equivalent in other architectures
to be able to write the necessary glue.

Probably we should just make it available on the arches that have the
necessary hardware facilities.

- Arnaldo