Re: [rfc] Describe events in a structured way via sysfs

[Robert Richter <robert.richter@amd.com>]

On 20.07.10 01:48:28, Lin Ming wrote:
 The caller reads config and type and pass them into perf_event_attr.
> 
> 1. Hardware events
> /sys/devices/system/cpu/cpu0...cpuN/events
> |-- L1-dcache-load-misses  ===> event name
> |   |-- config             ===> config value for the event
> |   `-- type               ===> event type

Wouldn't it be much easier to have a unique sysfs id (could be an
u64):

> |-- L1-dcache-load-misses  ===> event name
> |   `-- id                 ===> event id

... and then extend the syscall to enable an event by its sysfs id:

            memset(&attr, 0, sizeof(attr));
            attr.type        = PERF_TYPE_SYSFS;
            attr.sysfs_id    = sysfs_id;
            attr.sample_type = PERF_SAMPLE_CPU | PERF_SAMPLE_RAW;
            attr.config      = config;
	    ...

The kerrnel then knows which event is meant and the don't have to
provide event specific paramaters such as type/config that requires an
event specific setup. The advantage would be that we can open an event
file descriptor of every kind of event in a standardized way.

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center