Re: [RESEND][PATCH v2 1/3] sched/tp: Add new tracepoint to track uclamp set from user-space

[Lukasz Luba]

On 7/6/23 12:14, Peter Zijlstra wrote:
> On Wed, May 31, 2023 at 07:26:29PM +0100, Qais Yousef wrote:
> > On 05/22/23 15:57, Lukasz Luba wrote:
> > > The user-space can set uclamp value for a given task. It impacts task
> > > placement decisions made by the scheduler. This is very useful information
> > > and helps to understand the system behavior or track improvements in
> > > middleware and applications which start using uclamp mechanisms and report
> > > better performance in tests.
> >
> > Do you mind adding a generic one instead please? And explain why we can't just
> > attach to the syscall via kprobes? I think you want to bypass the permission
> > checks, so maybe a generic tracepoint after that might be justifiable?
> > Then anyone can use it to track how userspace has changed any attributes for
> > a task, not just uclamp.
>
> Yeah, so I'm leaning towards the same, if you want to put a tracepoint
> in __sched_setscheduler(), just trace the whole attr and leave it at
> that:
>
> 	trace_update_sched_attr_tp(p, attr);
>
> or somesuch.

OK, fair enough, I'll do that. Thanks Peter!
(I'm sorry for the delay, I was on vacation)

Lukasz