[PATCH v2 2/2] tools/gputop: toggle sysfs profiling knob if available for device

[Adrián Larumbe]

On 03.04.2024 15:46, Lucas De Marchi wrote:
> On Tue, Apr 02, 2024 at 11:27:45PM +0100, Adrián Larumbe wrote:
> > For every DRM device that enables its job accounting HW from user space,
> > toggle it right before obtaining per-client fdinfo numbers.
> > 
> > Make sure profiling status is returned to its original state before
> > exiting, by handling the SIGINT signal just like in intel_gpu_top.
> 
> isn't this something that should be rather tracked on the kernel side
> rather than relying on the userspace to behave?

This would simplify handling of the sysfs knob state from user space, but I'm
not sure normal sysfs device attributes are allowed to keep an internal state
between _show() calls.

> 1) call gputop
> 2) call gputop, because you forgot you had it open in another ssh
>    session
> 3) stop (1), because ssh session dies

I feel tempted to brush this off as legitimate behaviour, albeit 'undefined'.
If we cannot handle the scenario in which multiple profilers tweak the profiling
state at the same time from kernel space, then I would prefer to expect users to
readjust the sysfs attribute value manually.

> From the kernel side, I think it could be done by enabling it on fd
> open, disabling it on last close.

Adrian Larumbe