From: Keith Packard <keithp@keithp.com>
To: Daniel Vetter <daniel@ffwll.ch>, Eric Anholt <eric@anholt.net>
Cc: intel-gfx@lists.freedesktop.org, "Dodonov,
Eugeni" <eugeni.dodonov@intel.com>
Subject: Re: gen7 missed IRQ workaround series.
Date: Tue, 03 Jan 2012 15:38:25 -0800 [thread overview]
Message-ID: <86lipomk5q.fsf@sumi.keithp.com> (raw)
In-Reply-To: <CAKMK7uHt6y+v7ptwekL-CM4SvQiUUvnwVwR_=kc5rGAtoDo-aA@mail.gmail.com>
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On Wed, 4 Jan 2012 00:04:18 +0100, Daniel Vetter <daniel@ffwll.ch> wrote:
> I kinda prefer Chris' approach of sticking with irqs, but backing it up
> with a timer in the msec range. Can't find that patch though atm (iirc
> it's in bugzilla somewhere).
I think we've resolved that the interrupt arrives, but that it is not
serialized wrt the memory write. So, what I'd love to see is whether
waiting for the irq and then busy looping for 'a while' works. This
would allow for long-running operations to idle the CPU and then hit the
interrupt and spin until the memory write is recognized.
Any solution which can leave operations unacknowledged for 'ms'
timeframes seems like a potential for serious performance
problems. Eric's simple spinning approach seems fine for the BLT ring
which we don't use that often; something more complicated and yet not
entirely timer-based might be more efficient for longer-running operations.
--
keith.packard@intel.com
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next prev parent reply other threads:[~2012-01-03 23:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-22 22:54 gen7 missed IRQ workaround series Eric Anholt
2011-12-22 22:54 ` [PATCH 1/3] drm/i915: Do the fallback non-IRQ wait in ring throttle, too Eric Anholt
2011-12-22 22:55 ` [PATCH 2/3] drm/i915: Work around gen7 BLT ring synchronization issues Eric Anholt
2011-12-22 22:55 ` [PATCH 3/3] drm/i915: Make the fallback IRQ wait not sleep Eric Anholt
2012-01-02 18:25 ` gen7 missed IRQ workaround series Eugeni Dodonov
2012-01-02 20:17 ` Kenneth Graunke
2012-01-03 23:04 ` Daniel Vetter
2012-01-03 23:38 ` Keith Packard [this message]
2012-01-04 17:02 ` Daniel Vetter
2012-01-04 17:05 ` Keith Packard
2012-01-04 17:24 ` Daniel Vetter
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