[PATCH 06/13] drm/i915: Only grab timestamps when needed

Tvrtko Ursulin
2016-01-08T11:30:02Z

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

No need to call ktime_get_raw_ns twice per unlimited wait and can
also elimate a local variable.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/i915_gem.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index de98dc41fb9f..c4f69579eb7a 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1246,7 +1246,7 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
int state = interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
DEFINE_WAIT(wait);
unsigned long timeout_expire;
- s64 before, now;
+ s64 before = 0;
int ret;

WARN(!intel_irqs_enabled(dev_priv), "IRQs disabled");
@@ -1266,14 +1266,17 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
return -ETIME;

timeout_expire = jiffies + nsecs_to_jiffies_timeout(*timeout);
+
+ /*
+ * Record current time in case interrupted by signal, or wedged.
+ */
+ before = ktime_get_raw_ns();
}

if (INTEL_INFO(dev_priv)->gen >= 6)
gen6_rps_boost(dev_priv, rps, req->emitted_jiffies);

- /* Record current time in case interrupted by signal, or wedged */
trace_i915_gem_request_wait_begin(req);
- before = ktime_get_raw_ns();

/* Optimistic spin for the next jiffie before touching IRQs */
ret = __i915_spin_request(req, state);
@@ -1331,11 +1334,10 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
finish_wait(&ring->irq_queue, &wait);

out:
- now = ktime_get_raw_ns();
trace_i915_gem_request_wait_end(req);

if (timeout) {
- s64 tres = *timeout - (now - before);
+ s64 tres = *timeout - (ktime_get_raw_ns() - before);

*timeout = tres < 0 ? 0 : tres;

--
1.9.1