From: "Dixit, Ashutosh" <ashutosh.dixit@intel.com>
To: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 4/7] drm/i915/perf: add new open param to configure polling of OA buffer
Date: Thu, 12 Mar 2020 15:20:53 -0700 [thread overview]
Message-ID: <87sgidw6yi.wl-ashutosh.dixit@intel.com> (raw)
In-Reply-To: <b5702235-df19-e74b-9518-98b63d200706@intel.com>
On Thu, 12 Mar 2020 13:37:12 -0700, Lionel Landwerlin wrote:
> On 12/03/2020 21:27, Dixit, Ashutosh wrote:
> > On Tue, 03 Mar 2020 14:19:02 -0800, Umesh Nerlige Ramappa wrote:
> >> From: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
> >>
> >> This new parameter let's the application choose how often the OA
> >> buffer should be checked on the CPU side for data availability. Longer
> >> polling period tend to reduce CPU overhead if the application does not
> >> care about somewhat real time data collection.
> >>
> >> v2: Allow disabling polling completely with 0 value (Lionel)
> >> v3: Version the new parameter (Joonas)
> >> v4: Rebase (Umesh)
> > Hi Lionel, I was thinking that one way to keep things simple for now (and
> > fix the high cpu usage issue) would be to expose _ONLY_ this OA poll period
> > parameter to user space. That is we don't expose the interrupt or the flush
> > ioctl to user space at this time. This way the user will be able to
> > configure the hrtimer frequency to a lower value to bring down the cpu
> > usage.
> >
> > Also we would disallow disabling the timer (and internally also not use the
> > interrupt). So everything will happen in exactly the same way as it used to
> > (no other changes needed) but at a lower rate if the user so chooses.
> >
> > What do you think about this?
> >
> > Thanks!
> > --
> > Ashutosh
>
> Sure, just make sure the users know about this.
Ok, so the plan now is to just post and review/merge the first 4 patches
mostly as is, except that the poll timer cannot be disabled. IMO this
should solve the cpu usage issue. Then we can take up the remaining 3
interrupt and flush patches and see if they are really needed and move them
forward if they are.
> The fact that they can now select timer values that will potentially lead
> to the loss of the buffer's data because it was overridden.
I think you mean over-written. You are right but I think there is way
around this and we can post that patch soon which I think will avoid this
issue too.
Thanks!
--
Ashutosh
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next prev parent reply other threads:[~2020-03-12 22:21 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-03 22:18 [Intel-gfx] [PATCH 0/7] drm/i915/perf: add OA interrupt support Umesh Nerlige Ramappa
2020-03-03 22:18 ` [Intel-gfx] [PATCH 1/7] drm/i915/perf: rework aging tail workaround Umesh Nerlige Ramappa
2020-03-03 22:19 ` [Intel-gfx] [PATCH 2/7] drm/i915/perf: move pollin setup to non hw specific code Umesh Nerlige Ramappa
2020-03-03 22:19 ` [Intel-gfx] [PATCH 3/7] drm/i915/perf: only append status when data is available Umesh Nerlige Ramappa
2020-03-03 22:19 ` [Intel-gfx] [PATCH 4/7] drm/i915/perf: add new open param to configure polling of OA buffer Umesh Nerlige Ramappa
2020-03-12 19:27 ` Dixit, Ashutosh
2020-03-12 20:37 ` Lionel Landwerlin
2020-03-12 22:20 ` Dixit, Ashutosh [this message]
2020-03-12 23:10 ` Umesh Nerlige Ramappa
2020-03-03 22:19 ` [Intel-gfx] [PATCH 5/7] drm/i915: handle interrupts from the OA unit Umesh Nerlige Ramappa
2020-03-03 22:19 ` [Intel-gfx] [PATCH 6/7] drm/i915/perf: add interrupt enabling parameter Umesh Nerlige Ramappa
2020-03-04 5:47 ` Dixit, Ashutosh
2020-03-04 8:55 ` Lionel Landwerlin
2020-03-10 20:08 ` Umesh Nerlige Ramappa
2020-03-10 20:57 ` Lionel Landwerlin
2020-03-03 22:19 ` [Intel-gfx] [PATCH 7/7] drm/i915/perf: add flushing ioctl Umesh Nerlige Ramappa
2020-03-04 5:48 ` Dixit, Ashutosh
2020-03-04 8:52 ` Lionel Landwerlin
2020-03-05 5:56 ` Dixit, Ashutosh
2020-03-09 19:51 ` Umesh Nerlige Ramappa
2020-03-10 20:44 ` Lionel Landwerlin
2020-03-11 3:05 ` Dixit, Ashutosh
2020-03-09 21:15 ` Umesh Nerlige Ramappa
2020-03-04 2:53 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/i915/perf: add OA interrupt support (rev5) Patchwork
2020-03-04 2:58 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2020-03-04 3:13 ` [Intel-gfx] ✗ Fi.CI.DOCS: " Patchwork
2020-03-04 3:18 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2020-03-04 19:31 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
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