Re: [RFC][PATCH] perf: sysfs type id

[Stephane Eranian]

Peter,

On Tue, Nov 9, 2010 at 10:45 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> The below is a RFC patch adding dynamic type ids to perf.
>
> We need to represent PMUs in sysfs because we want to allow multiple
> (loadable) PMUs and need a way to identify them.
>
> This patch creates a new device class "pmu" and adds a single attribute
> "type" to it. This device attribute will expose the dynamic type id as
> required by perf_event_attr::type.
>
> The sysfs layout looks like:
>
> [root@westmere ~]# cd /sys/class/pmu/
> [root@westmere pmu]# ls -la
> total 0
> drwxr-xr-x Â2 root root 0 2010-11-09 22:22 .
> drwxr-xr-x 47 root root 0 2010-11-09 22:22 ..
> lrwxrwxrwx Â1 root root 0 2010-11-09 22:22 breakpoint -> ../../devices/virtual/pmu/breakpoint
> lrwxrwxrwx Â1 root root 0 2010-11-09 22:22 cpu -> ../../devices/virtual/pmu/cpu
> lrwxrwxrwx Â1 root root 0 2010-11-09 22:22 frob -> ../../devices/virtual/pmu/frob
> lrwxrwxrwx Â1 root root 0 2010-11-09 22:22 software -> ../../devices/virtual/pmu/software
> lrwxrwxrwx Â1 root root 0 2010-11-09 22:22 tracepoint -> ../../devices/virtual/pmu/tracepoint
> [root@westmere pmu]# cd frob/
> [root@westmere frob]# ls -la
> total 0
> drwxr-xr-x 3 root root  Â0 2010-11-09 22:22 .
> drwxr-xr-x 7 root root  Â0 2010-11-09 22:22 ..
> drwxr-xr-x 2 root root  Â0 2010-11-09 22:23 power
> lrwxrwxrwx 1 root root  Â0 2010-11-09 22:23 subsystem -> ../../../../class/pmu
> -r--r--r-- 1 root root 4096 2010-11-09 22:23 type
> -rw-r--r-- 1 root root 4096 2010-11-09 22:22 uevent
> [root@westmere frob]# cat type
> 6

And then, what do you do with 6?
I assume you have to pass it in the attr struct.
How do you plan on doing this while keeping what is already there?
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