[Intel-gfx] [PATCH 2/5] drm/i915: Expose list of clients in sysfs

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-12-16 13:28:18)
> 
> On 16/12/2019 13:17, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2019-12-16 12:07:01)
> >> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >>
> >> Expose a list of clients with open file handles in sysfs.
> >>
> >> This will be a basis for a top-like utility showing per-client and per-
> >> engine GPU load.
> >>
> >> Currently we only expose each client's pid and name under opaque numbered
> >> directories in /sys/class/drm/card0/clients/.
> >>
> >> For instance:
> >>
> >> /sys/class/drm/card0/clients/3/name: Xorg
> >> /sys/class/drm/card0/clients/3/pid: 5664
> > 
> > Should we even bother having the name here? And just have a link to pid
> > instead? Contemplating even pidfd for ultramodern.
> 
> I haven't looked at what symlink creation facilities sysfs would allow. 
> But even then, I don't see how we could link to proc from sysfs.
> 
> I had a quick read on pidfd and don't see how it fits. What did you have 
> in mind?

Just thinking if we should do something like 
	pidfd = open(/.../clients/3/pid);

Ok, looking at pidfd_fops, it doesn't provide anything useful like being
able to safely acquire the pid->comm. Shame.
-Chris