Re: [PATCH 3/4] perf tools: Add attr<num> syntax to event parser

From: Jiri Olsa
Date: Mon Jun 03 2013 - 09:55:10 EST


On Fri, May 31, 2013 at 11:16:24AM +0200, Robert Richter wrote:
> From: Robert Richter <robert.richter@xxxxxxxxxxx>
>
> The event parser is limited to update only a subset of all fields in
> struct perf_event_attr (config*, period, branch_type). We are not able
> to set other attr fields, esp. flags.
>
> Introducing a new syntax to set any field of the event attribute by
> using an index to the u64 value to be used within struct
> perf_event_attr. The new syntax attr<num> is similar to config<num>,
> but <num> specifies the index to be used. E.g. attr5:23 sets bit 23 of
> the flag field of attr.
>
> The persistent event implementation is a use case of the above. In
> this case sysfs provides:
>
> /sys/bus/event_source/devices/persistent/events/mce_record:persistent,config=106
> /sys/bus/event_source/devices/persistent/format/persistent:attr5:23

good idea, you probably need to update:
Documentation/ABI/testing/sysfs-bus-event_source-devices-format

also.. there's so far only mce_record event AFAICS, and this seems
to be initialized at the time when sysfs's not ready so I dont get
the sysfs entries for it.. and since there's no other event yet,
the sysfs is not updated/populated later.. I think ;)

I'll probably tweak it somehow later, but if there was anything
simple I could do or I missed something please let me know, that
would speed up my testing

thanks,
jirka
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