Re: [PATCH RFC] hist lookups

Jiri Olsa
2018-11-11T19:42:02Z

On Sun, Nov 11, 2018 at 08:41:32PM +0100, Jiri Olsa wrote:
> On Thu, Nov 08, 2018 at 05:07:21PM -0800, David Miller wrote:
> > From: Jiri Olsa <jolsa@redhat.com>
> > Date: Thu, 8 Nov 2018 08:13:03 +0100
> >
> > > we could separated fork/mmaps to separate dummy event map, or just
> > > parse them out in the read thread and create special queue for them
> > > and drop just samples in case we are behind
> >
> > What you say at the end here is basically what I am proposing.
> >
> > Perf dequeues events from mmap ring as fast as possible.
> >
> > Perf has two internal queues, high priority and low priority.
> >
> > High priority events are never dropped.
> >
> > Low priority events are dropped on overload, oldest first.
>
> I added the dropping logic, it's simple so far..
>
> the processing thread will drop (not process) samples
> which gets behind the latest event time more then
> the 'refresh rate' seconds
>
> adding separate queues for samples and other events is
> possible, but it looks like the above simple solution
> could be ok for now

I pushed it to my perf/fixes branch

jirka