Messages in this thread | | | Date | Tue, 11 Sep 2012 08:32:55 -0600 | From | David Ahern <> | Subject | Re: [PATCH 3/3] perf tool: give user better message if precise is not supported |
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On 9/11/12 8:01 AM, Robert Richter wrote: > > Ok, wrong question. Better would have been: Did you run it on a > non-pebs Intel machine of an non-ibs AMD machine?
Intel: yes. VM for example. All the servers I have now are Nehalem or better - ie., with a PEBS.
AMD: no. I do not have any AMD-based servers.
> >> I do not post patches without testing them. This particular patch was >> verified in a Virtual Machine (no PEBS) and using :pG modifier. >> >> 'egrep -r ENOTSUP tools/perf' shows hits in 3 other files, so I am not >> the only one using the shortcut. I'll change it in the follow up with >> better commit messages to make it consistent with patch 2. > > For VM this might be valid. Don't know where ENOTSUP comes from. It is > neither in kernel/events/ nor arch/x86/kernel/cpu/perf.
My guess would be /usr/include/bits/errno.h:
/* Linux has no ENOTSUP error code. */ # define ENOTSUP EOPNOTSUPP
> > If you run this bare-metal on older machines which do not support pebs > or ibs, the syscall returns EOPNOTSUPP. You can trigger the same > behaviour on newer systems with: > > # perf record -e cycles:ppp -c 2097120 -R -a sleep 1 > > Error: sys_perf_event_open() syscall returned with 95 (Operation not supported). /bin/dmesg may provide additional information. > ... > > It should work in this case too.
The commit message was a copy and paste from the failure of both :p in a VM (PEBS is not supported in a VM). I also ran the bare metal case with :pG which per the second patch in this series generates the not supported message.
David
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