[Intel-gfx] [PATCH 3.0-rc3] i915: Fix gen6 (SNB) GPU stalling

[Sun, Yi]

All,
Thank for Mengmeng’s testing work, now the status is as following:

The bug33394(performance regression: screen stuttered when running the demo of 3D games with compiz enabled without GPU semaphores) is fixed. The two issue(stutter and hangcheck) is gone, now.
The issue described as bug 36407 isn’t able to be reproduced.
The bug 36653 is still there.

As to the performance, the detail is listed as the table.
From the table, we can get the information that the patch make little effect to the 2D performance, but it improve 3D performance much.

　

without patch

with patch

　

dis-semaphores

en-semaphores

dis-semaphores

en-semaphores

2D-aa10text

1790k

2650k

1640k

2550k

2D-rgb10text

1380k

2380k

1100k

2320k

openarena

11

86.2

98.9

103.9 fps

urbanterror

10.5

71.4

68.5

70.9 fps

padman

12.1

100.7

92

100.3 fps

nexuiz

6

20

19.5

20 fps



Thanks
   --Yi,Sun




-----Original Message-----
From: intel-gfx-bounces+yi.sun=intel.com at lists.freedesktop.org [mailto:intel-gfx-bounces+yi.sun=intel.com at lists.freedesktop.org] On Behalf Of Daniel J Blueman
Sent: Wednesday, June 15, 2011 12:52 AM
To: Eric Anholt
Cc: Daniel J Blueman; intel-gfx at lists.freedesktop.org; linux-kernel at vger.kernel.org; Dave Airlie
Subject: [Intel-gfx] [PATCH 3.0-rc3] i915: Fix gen6 (SNB) GPU stalling



On 14 June 2011 13:23, Eric Anholt <eric at anholt.net> wrote:

> On Tue, 14 Jun 2011 12:18:36 +0800, Daniel J Blueman <daniel.blueman at gmail.com> wrote:

>> Hi Eric,

>>

>> The frequent ~1.5s pauses I hit with SNB hardware in the gnome3 UI (eg

>> whenever you hit the top-left of the screen to show all windows) are

>> nicely addressed by your recent wake patch [1] (ported to -rc3). Thus

>> I see no 'missed IRQ' kernel messages.

>>

>> As this addresses a significant usability regression, are you happy to

>> add it to the 3.0-rc queue? I think it has very good value in -stable

>> also (assuming correctness). What do you think?

>

> This one had significant performance impacts, and later hacks in this

> series worked around the problem to approximately the same level of

> success with less impact, and we don't actually have a justification of

> why any of them work.  We were still hoping to come up with some clue,

> and haven't yet.



True; that is quite heavy handed delay looping.



It's a pity the usual Intel font didn't make it to the programmer's

reference manuals. Anyway, unmasking the blitter user interrupt in the hardware

status mask register addresses the root cause. Out of reset it's FFFFFFFFh,

so we don't need to read it here.



It would be good to get this into -rc4. -stable probably needs some additional

tweaks.



Signed-off-by: Daniel J Blueman <daniel.blueman at gmail.com>

---

drivers/gpu/drm/i915/i915_irq.c |    6 ++++++

1 files changed, 6 insertions(+), 0 deletions(-)



diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c

index b9fafe3..9a98c1b 100644

--- a/drivers/gpu/drm/i915/i915_irq.c

+++ b/drivers/gpu/drm/i915/i915_irq.c

@@ -1827,6 +1827,12 @@ int ironlake_irq_postinstall(struct drm_device *dev)

                ironlake_enable_display_irq(dev_priv, DE_PCU_EVENT);

       }

+       if (IS_GEN6(dev))

+                /* allow blitter user interrupt to generate a MSI write from

+                   the ISR */

+                I915_WRITE(GEN6_BLITTER_HWSTAM,

+                          0xffffffff & ~GEN6_BLITTER_USER_INTERRUPT);

+

       return 0;

}

--

1.7.4.1



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