Messages in this thread | | | Date | Tue, 31 Jan 2012 16:47:56 -0800 | From | Corey Ashford <> | Subject | Re: [PATCH 5/9] perf: Adding sysfs group format attribute for pmu device |
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On 01/27/2012 01:19 PM, Peter Zijlstra wrote: > On Fri, 2012-01-27 at 13:08 -0800, Corey Ashford wrote: >> s an example, the IBM PowerEN processor has roughly 20 different PMU's >> on it. Some of those PMU's are quite complex and divide their events up >> into subsets, each with different fields. For example, some events may >> have a PID matching field, and others may have an bus number matching >> field, or matching mode field, etc. The fields are different widths, >> and may overlap in the config/1/2 space. >> >> It seems that there are two approaches you could take: >> >> 1) Keep your format, but allow the fields to overlap in the bit space. >> For example: >> >> "/sys/...<dev>/format/event" contains "config:0-7" >> "/sys/...<dev>/format/pidmatch" contains "config:8-15" >> "/sys/...<dev>/format/busmatch" contains "config:8-13" >> >> Note that busmatch overlaps pidmatch >> >> 2) Create event groups that have their overlapping config space >> separated out: >> >> "/sys/...<dev>/format/event" contains "config:0-7" >> >> "/sys/...<dev>.1/format/pidmatch" contains "config:8-15" >> >> "/sys/...<dev>.2/format/busmatch" contains "config:8-13" >> >> >> Notice the .1 and .2 on the <dev>. >> >> This might help the user understand which fields go together. I'm not >> sold on the .1 syntax... you could do it as <dev>.<event-group-name>/ or >> <dev>/<event-group-name>/... or whatever seems to make the most sense >> and is relatively easy to implement and use. > > Why try and stuff those 20 in a single driver? Have 20 drivers and each > their own format/ hierarchy.
I'm sure that could work. Since sysfs seems to be fairly independent (if necessary) of the hardware structure, I suppose this wouldn't be a problem.
What do you think of Jiri's (Jirka's ?) other ideas of subdividing the format directory?
- Corey
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