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

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Date:	Sat, 27 Oct 2012 22:34:27 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	Namhyung Kim <namhyung.kim@....com>
Subject: Re: [BUG] perf parser: does not support arbitrary new sysfs events

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 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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