From: Francisco Jerez <currojerez@riseup.net>
Date: Thu, 25 Nov 2010 15:37:17 +0000 (+0100)
Subject: drm/nouveau: Spin for a bit in nouveau_fence_wait() before yielding the CPU.
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=395a31ec7ed9b02c5412f4405acbd6fceacca0fc;p=linux-beck.git

drm/nouveau: Spin for a bit in nouveau_fence_wait() before yielding the CPU.

Sleeping doesn't pay off for very short delays in comparison with the
minimum granularity of schedule_timeout().

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
---

diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
index 2579fc69d182..abfeff19488e 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
@@ -218,6 +218,7 @@ int
 __nouveau_fence_wait(void *sync_obj, void *sync_arg, bool lazy, bool intr)
 {
 	unsigned long timeout = jiffies + (3 * DRM_HZ);
+	unsigned long sleep_time = jiffies + 1;
 	int ret = 0;
 
 	while (1) {
@@ -231,7 +232,7 @@ __nouveau_fence_wait(void *sync_obj, void *sync_arg, bool lazy, bool intr)
 
 		__set_current_state(intr ? TASK_INTERRUPTIBLE
 			: TASK_UNINTERRUPTIBLE);
-		if (lazy)
+		if (lazy && time_after_eq(jiffies, sleep_time))
 			schedule_timeout(1);
 
 		if (intr && signal_pending(current)) {