Re: [BUG] perf parser: does not support arbitrary new sysfs events

[Stephane Eranian]

On Sat, Oct 27, 2012 at 10:34 PM, Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> On Fri, Oct 26, 2012 at 10:23:09PM +0200, Stephane Eranian wrote:
>> Hi,
>>
>> The latest round of perf parser changes broke my PEBS-LL patch series
>> (at the last minute). For PEBS-LL, I need to add to generic events but I want
>> to keep them PMU specific. As such, they need to live in the sysfs events
>> subdir: /sys/devices/cpu/events/mem-loads, sys/devices/cpu/events/mem-stores.
>>
>> Given your latest rounds of sysfs event changes, I had to modify my kernel
>> patches to fit those two new events within your perf_pmu_events_attr tables.
>>
>> But now, when I try to do:
>>
>> $ perf record -e cpu/mem-loads/ ....
>
> I can try this only on on uncore events and hw events aliases and that seems to work
>
I know it works there. I don't understand why it does not work with cpu/.

Just add an encoding that has no hardcoded equivalent. I bet you will
reproduce the problem.

In my patch set, I have extended your perf_pmu_events_attr struct to
also accept an already preformed event_str. I can send you that extension
if you want.


>>
>> I get unsupported event. Looks at the syscall trace, it seems perf does not even
>> look into the sysfs subdir to find a possible match. I don't
>> understand that. What's
>> the point of sysfs event list if it is not used or cannot be extended?
>>
>> Note that when I explicitly pass the content of the sysfs file to perf
>> record, it
>> works:
>>
>> $ perf record -e cpu/event=0xcd,umask=0x1,ldlat=3/ ......
>>
>> So this is clearly a problem with the lookup in sysfs.
>>
>> Also if you have the mappings exposed now in sysfs, why keep the hardcoded
>> generic events as well? Or why have those events hardcoded in the parser as
>> well.
>
> having perf work on old kernels
>
>>
>> I don't understand all this parser code. I  get the feeling it is
>> getting a bit out of
>> hands already. But now, I am stuck. So could you fix my parser problem ASAP?
>
> yep, but need more details.. related patches would help
>
> jirka
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