Messages in this thread | | | Date | Mon, 12 Nov 2018 00:26:27 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH RFC] hist lookups |
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On Sun, Nov 11, 2018 at 03:08:01PM -0800, David Miller wrote: > From: Jiri Olsa <jolsa@redhat.com> > Date: Sun, 11 Nov 2018 20:41:32 +0100 > > > 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.. > > So for me perf top gets into a state where the samples counter stops > incrementing, but the event counter does keep moving (which is the > histogram code decaying histogram entries from the display thread). > > Which means the event processing has basically stopped. > > The event threads are not stuck in a loop, because they respond to > the "q" keypress and we can exit.
is the drop count showing something?
jirka
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