Attachment 80333 Details for Bug 65394 – Don't count semaphore waits towards a hang

[patch] Don't count semaphore waits towards a hang

0002-drm-i915-Don-t-count-semaphore-waits-towards-a-stuck.patch (text/plain), 3.33 KB, created by Chris Wilson on 2013-06-05 09:32:45 UTC

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Creator: Chris Wilson

Created: 2013-06-05 09:32:45 UTC

Size: 3.33 KB

patch

obsolete

>From 075b68c315c9f1c02565576e1f412029993472c0 Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Wed, 5 Jun 2013 10:08:35 +0100
>Subject: [PATCH 2/2] drm/i915: Don't count semaphore waits towards a stuck
> ring
>
>If we detect a ring is in a valid wait for another, just let it be.
>Eventually it will either begin to progress again, or the entire system
>will come grinding to a halt and then hangcheck will fire as soon as the
>deadlock is detected.
>
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>---
> drivers/gpu/drm/i915/i915_irq.c |   55 +++++++++++++++++++++++++++------------
> 1 file changed, 38 insertions(+), 17 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
>index e936fde..ae3e299 100644
>--- a/drivers/gpu/drm/i915/i915_irq.c
>+++ b/drivers/gpu/drm/i915/i915_irq.c
>@@ -2331,33 +2331,50 @@ static bool i915_hangcheck_ring_idle(struct intel_ring_buffer *ring,
> 	return false;
> }
> 
>-static bool semaphore_passed(struct intel_ring_buffer *ring)
>+static struct intel_ring_buffer *
>+semaphore_waits_for(struct intel_ring_buffer *ring, u32 *acthd)
> {
> 	struct drm_i915_private *dev_priv = ring->dev->dev_private;
>-	u32 acthd = intel_ring_get_active_head(ring) & HEAD_ADDR;
>-	struct intel_ring_buffer *signaller;
> 	u32 cmd, ipehr, acthd_min;
> 
> 	ipehr = I915_READ(RING_IPEHR(ring->mmio_base));
> 	if ((ipehr & ~(0x3 << 16)) !=
> 	    (MI_SEMAPHORE_MBOX | MI_SEMAPHORE_COMPARE | MI_SEMAPHORE_REGISTER))
>-		return false;
>+		return NULL;
> 
> 	/* ACTHD is likely pointing to the dword after the actual command,
> 	 * so scan backwards until we find the MBOX.
> 	 */
>-	acthd_min = max((int)acthd - 3 * 4, 0);
>+	*acthd = intel_ring_get_active_head(ring) & HEAD_ADDR;
>+	acthd_min = max((int)*acthd - 3 * 4, 0);
> 	do {
>-		cmd = ioread32(ring->virtual_start + acthd);
>+		cmd = ioread32(ring->virtual_start + *acthd);
> 		if (cmd == ipehr)
> 			break;
> 
>-		acthd -= 4;
>-		if (acthd < acthd_min)
>-			return false;
>+		*acthd -= 4;
>+		if (*acthd < acthd_min)
>+			return NULL;
> 	} while (1);
> 
>-	signaller = &dev_priv->ring[(ring->id + (((ipehr >> 17) & 1) + 1)) % 3];
>+	return &dev_priv->ring[(ring->id + (((ipehr >> 17) & 1) + 1)) % 3];
>+}
>+
>+static int semaphore_passed(struct intel_ring_buffer *ring)
>+{
>+	struct drm_i915_private *dev_priv = ring->dev->dev_private;
>+	struct intel_ring_buffer *signaller;
>+	u32 acthd, ctl;
>+
>+	signaller = semaphore_waits_for(ring, &acthd);
>+	if (signaller == NULL || signaller == ring)
>+		return -1;
>+
>+	/* cursory check for an unkickable deadlock */
>+	ctl = I915_READ_CTL(signaller);
>+	if (ctl & RING_WAIT_SEMAPHORE && semaphore_passed(signaller) <= 0)
>+		return -1;
>+
> 	return i915_seqno_passed(signaller->get_seqno(signaller, false),
> 				 ioread32(ring->virtual_start+acthd+4)+1);
> }
>@@ -2374,13 +2391,17 @@ static bool kick_ring(struct intel_ring_buffer *ring)
> 		return true;
> 	}
> 
>-	if (INTEL_INFO(dev)->gen >= 6 &&
>-	    tmp & RING_WAIT_SEMAPHORE &&
>-	    semaphore_passed(ring)) {
>-		DRM_ERROR("Kicking stuck semaphore on %s\n",
>-			  ring->name);
>-		I915_WRITE_CTL(ring, tmp);
>-		return true;
>+	if (INTEL_INFO(dev)->gen >= 6 && tmp & RING_WAIT_SEMAPHORE) {
>+		switch (semaphore_passed(ring)) {
>+		default:
>+			return false;
>+		case 1:
>+			DRM_ERROR("Kicking stuck semaphore on %s\n",
>+				  ring->name);
>+			I915_WRITE_CTL(ring, tmp);
>+		case 0:
>+			return true;
>+		}
> 	}
> 	return false;
> }
>-- 
>1.7.10.4
>

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Attachments on bug 65394: 80326 | 80331 | 80333 | 80335

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