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Commit 24a65e62 authored by Mika Kuoppala's avatar Mika Kuoppala Committed by Mika Kuoppala
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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: default avatarMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1456930109-21532-1-git-send-email-mika.kuoppala@intel.com
parent d431440c

drivers/gpu/drm/i915/i915_debugfs.c

+0 −2
Original line number Diff line number Diff line
@@ -1367,8 +1367,6 @@ static int i915_hangcheck_info(struct seq_file *m, void *unused) 
		seq_printf(m, "\tACTHD = 0x%08llx [current 0x%08llx]\n",

			   (long long)ring->hangcheck.acthd,

			   (long long)acthd[i]);

		seq_printf(m, "\tmax ACTHD = 0x%08llx\n",

			   (long long)ring->hangcheck.max_acthd);

		seq_printf(m, "\tscore = %d\n", ring->hangcheck.score);

		seq_printf(m, "\taction = %d\n", ring->hangcheck.action);

drivers/gpu/drm/i915/i915_gpu_error.c

+0 −2
Original line number Diff line number Diff line
@@ -230,8 +230,6 @@ static const char *hangcheck_action_to_str(enum intel_ring_hangcheck_action a) 
		return "wait";

	case HANGCHECK_ACTIVE:

		return "active";

	case HANGCHECK_ACTIVE_LOOP:

		return "active (loop)";

	case HANGCHECK_KICK:

		return "kick";

	case HANGCHECK_HUNG:

drivers/gpu/drm/i915/i915_irq.c

+7 −10
Original line number Diff line number Diff line
@@ -3001,14 +3001,9 @@ head_stuck(struct intel_engine_cs *ring, u64 acthd) 
		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;

	}



	if (!subunits_stuck(ring))

		return HANGCHECK_ACTIVE;
@@ -3083,6 +3078,7 @@ static void i915_hangcheck_elapsed(struct work_struct *work) 
#define BUSY 1

#define KICK 5

#define HUNG 20

#define ACTIVE_DECAY 15



	if (!i915.enable_hangcheck)

		return;
@@ -3151,9 +3147,8 @@ static void i915_hangcheck_elapsed(struct work_struct *work) 
				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 @@ static void i915_hangcheck_elapsed(struct work_struct *work) 
			 * 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));

drivers/gpu/drm/i915/intel_ringbuffer.h

+0 −2
Original line number Diff line number Diff line
@@ -79,7 +79,6 @@ enum intel_ring_hangcheck_action { 
	HANGCHECK_IDLE = 0,

	HANGCHECK_WAIT,

	HANGCHECK_ACTIVE,

	HANGCHECK_ACTIVE_LOOP,

	HANGCHECK_KICK,

	HANGCHECK_HUNG,

};
@@ -88,7 +87,6 @@ enum intel_ring_hangcheck_action { 


struct intel_ring_hangcheck {

	u64 acthd;

	u64 max_acthd;

	u32 seqno;

	int score;

	enum intel_ring_hangcheck_action action;