From: Chris Wilson
> Sent: 15 January 2020 20:53
>
> Since we may try and flush the cachelines associated with large buffers
> (an 8K framebuffer is about 128MiB, even before we try HDR), this leads
> to unacceptably long latencies (when using a voluntary CONFIG_PREEMPT).
> If we call cond_resche
From: David Laight
> Sent: 16 January 2020 14:41
> > I'll do some measurements later this afternoon.
>
> This is an Ivy bridge cpu, so clflush (not clflushopt).
> With a cond_resched for every page I get:
> (Note these calls are every 10 seconds)
For comparison some times booted with the orig
> I'll do some measurements later this afternoon.
This is an Ivy bridge cpu, so clflush (not clflushopt).
With a cond_resched for every page I get:
(Note these calls are every 10 seconds)
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | |
Quoting David Laight (2020-01-16 13:58:44)
> From: Chris Wilson
> > Sent: 16 January 2020 12:29
> >
> > Quoting David Laight (2020-01-16 12:26:45)
> > > However there is a call from __i915_gem_objet_set_pages() that
> > > is preceded by a lockdep_assert_held() check - so mustn't sleep.
> >
> > T
From: Chris Wilson
> Sent: 16 January 2020 12:29
>
> Quoting David Laight (2020-01-16 12:26:45)
> > However there is a call from __i915_gem_objet_set_pages() that
> > is preceded by a lockdep_assert_held() check - so mustn't sleep.
>
> That is a mutex; it's allowed to sleep. The might_sleep() he
From: Chris Wilson
> Sent: 16 January 2020 07:40
> Quoting Daniel Vetter (2020-01-16 06:52:42)
> > On Wed, Jan 15, 2020 at 08:52:45PM +, Chris Wilson wrote:
> > > Since we may try and flush the cachelines associated with large buffers
> > > (an 8K framebuffer is about 128MiB, even before we tr
Quoting David Laight (2020-01-16 12:26:45)
> However there is a call from __i915_gem_objet_set_pages() that
> is preceded by a lockdep_assert_held() check - so mustn't sleep.
That is a mutex; it's allowed to sleep. The might_sleep() here should
help assuage your fears.
-Chris
_
Quoting Daniel Vetter (2020-01-16 06:52:42)
> On Wed, Jan 15, 2020 at 08:52:45PM +, Chris Wilson wrote:
> > Since we may try and flush the cachelines associated with large buffers
> > (an 8K framebuffer is about 128MiB, even before we try HDR), this leads
> > to unacceptably long latencies (whe
On Wed, Jan 15, 2020 at 08:52:45PM +, Chris Wilson wrote:
> Since we may try and flush the cachelines associated with large buffers
> (an 8K framebuffer is about 128MiB, even before we try HDR), this leads
> to unacceptably long latencies (when using a voluntary CONFIG_PREEMPT).
> If we call co
Since we may try and flush the cachelines associated with large buffers
(an 8K framebuffer is about 128MiB, even before we try HDR), this leads
to unacceptably long latencies (when using a voluntary CONFIG_PREEMPT).
If we call cond_resched() between each sg chunk, that it about every 128
pages, we
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