Re: [RFC PATCH] sched: Add cpu based entries to debugfs

[David Ahern <david.ahern@oracle.com>]

On 3/30/15 1:44 AM, Peter Zijlstra wrote:
> On Sun, Mar 29, 2015 at 10:13:33PM -0400, David Ahern wrote:
>> Before spending too much time formalizing this I wanted to see if you guys
>> would entertain the idea of making this info available via debugfs. It does
>> move the existing sched_features file to sched/features -- not sure how
>> acceptable it is to move files in debugfs.
>
> There also already is a /proc/sys/kernel/sched_domain/ sysctl thing that
> has much of the stuff in.
>
> I'm not opposed to a debugfs thing, but only if we can take the sysctl
> thing out.
>

Related files I aware of; perhaps there are others:

- /sys/devices/system/cpu entries. e.g., for cpu topology (physical 
package id, core id, sibling cores and threads)

- debufs file for sched_features

- /proc/sys/kernel/sched_domain for tweaking scheduling parameters

I could not find anything that shows the sched_domain information. The 
proposal here was to create read-only debugfs files to dump the same 
info (but with better readability for large systems) that comes with the 
sched_debug parameter. I chose debugfs because a) sched_features is 
there and b) it is debug information about the scheduler.

I could just as easily out it under /proc/sys/kernel/sched_domain or 
create a sched subdir under /sys/devices/system/cpu/cpu$n if one of 
those is preferred.

David