Re: [PATCH v2] mm: emit tracepoint when RSS changes by threshold

From: Michal Hocko
Date: Thu Sep 05 2019 - 10:43:15 EST

[Add Steven]

On Wed 04-09-19 12:28:08, Joel Fernandes wrote:
> On Wed, Sep 4, 2019 at 11:38 AM Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> >
> > On Wed 04-09-19 11:32:58, Joel Fernandes wrote:
> > > but also for reducing
> > > tracing noise. Flooding the traces makes it less useful for long traces and
> > > post-processing of traces. IOW, the overhead reduction is a bonus.
> >
> > This is not really anything special for this tracepoint though.
> > Basically any tracepoint in a hot path is in the same situation and I do
> > not see a point why each of them should really invent its own way to
> > throttle. Maybe there is some way to do that in the tracing subsystem
> > directly.
> I am not sure if there is a way to do this easily. Add to that, the fact that
> you still have to call into trace events. Why call into it at all, if you can
> filter in advance and have a sane filtering default?
> The bigger improvement with the threshold is the number of trace records are
> almost halved by using a threshold. The number of records went from 4.6K to
> 2.6K.

Steven, would it be feasible to add a generic tracepoint throttling?
Michal Hocko