Re: [RFC][PATCH v1 02/15] perf: export generic hardware events via sysfs

[Corey Ashford <cjashfor@linux.vnet.ibm.com>]

On 07/27/2010 01:27 AM, Robert Richter wrote:
> On 26.07.10 22:18:23, Lin Ming wrote:
>
>>>> /sys/devices/system/cpu/cpu0/events
>>>> |-- L1-dcache-load-misses
>>>> |   |-- config
>>>> |   `-- type
>
> vs.
>
>>>   |-- L1-dcache-load-misses  ===>  event name
>>>   |   `-- id                 ===>  event id
>
>>> This is very simple and flexible and solves the original problem too.
>>
>> Yeah, this is flexible. I'll think about this closely.
>
> The thing is, if you start introducing the config/type i/f, we will
> stick with it for a long time. I want to avoid this from the
> beginning.
>
> Using an id only would work with your current implementation too, you
> only need to maintain an id ->  config/type mapping, maybe in some
> private data section, without exporting it to userspace.

Now that I understand that the sysfs id essentially points to a kernel 
data structure, I like this idea a lot.  Before I was thinking that you 
were trying to place a lot of info into the id itself.

The only downside I see, and maybe it's a very minor one, is that you'll 
no longer have the ability to specify an event without specifying a 
sysfs path... there's no other mechanism.

- Corey