drm/i915/hangcheck: Prevent long walks across full-ppgtt
With full-ppgtt, it takes the GPU an eon to traverse the entire 256PiB
address space, causing a loop to be detected. Under the current scheme,
if ACTHD walks off the end of a batch buffer and into an empty
address space, we "never" detect the hang. If we always increment the
score as the ACTHD is progressing then we will eventually timeout (after
~46.5s (31 * 1.5s) without advancing onto a new batch). To counter act
this, increase the amount we reduce the score for good batches, so that
only a series of almost-bad batches trigger a full reset. DoS detection
suffers slightly but series of long running shader tests will benefit.
Based on a patch from Chris Wilson.
Testcase: igt/drv_hangman/hangcheck-unterminated
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1456930109-21532-1-git-send-email-mika.kuoppala@intel.com
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index d1a46ef..53e5104 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -3001,12 +3001,7 @@
memset(ring->hangcheck.instdone, 0,
sizeof(ring->hangcheck.instdone));
- if (acthd > ring->hangcheck.max_acthd) {
- ring->hangcheck.max_acthd = acthd;
- return HANGCHECK_ACTIVE;
- }
-
- return HANGCHECK_ACTIVE_LOOP;
+ return HANGCHECK_ACTIVE;
}
if (!subunits_stuck(ring))
@@ -3083,6 +3078,7 @@
#define BUSY 1
#define KICK 5
#define HUNG 20
+#define ACTIVE_DECAY 15
if (!i915.enable_hangcheck)
return;
@@ -3151,9 +3147,8 @@
switch (ring->hangcheck.action) {
case HANGCHECK_IDLE:
case HANGCHECK_WAIT:
- case HANGCHECK_ACTIVE:
break;
- case HANGCHECK_ACTIVE_LOOP:
+ case HANGCHECK_ACTIVE:
ring->hangcheck.score += BUSY;
break;
case HANGCHECK_KICK:
@@ -3172,10 +3167,12 @@
* attempts across multiple batches.
*/
if (ring->hangcheck.score > 0)
- ring->hangcheck.score--;
+ ring->hangcheck.score -= ACTIVE_DECAY;
+ if (ring->hangcheck.score < 0)
+ ring->hangcheck.score = 0;
/* Clear head and subunit states on seqno movement */
- ring->hangcheck.acthd = ring->hangcheck.max_acthd = 0;
+ ring->hangcheck.acthd = 0;
memset(ring->hangcheck.instdone, 0,
sizeof(ring->hangcheck.instdone));