On 20/05/16 13:20, Chris Wilson wrote:
On Thu, May 19, 2016 at 04:44:03PM +0100, Tvrtko Ursulin wrote:
On 19/05/16 12:32, Chris Wilson wrote:
Avoid the two calls to ktime_get_raw_ns() (at best it reads the TSC) as
we only need to compute the elapsed time for a timed wait.
v2: Eliminate the unused local variable reducing the function size by 64
bytes (using the storage space on the callers stack rather than adding
to our stack frame)
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b48a3b46e86f..2c254cf49c15 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1215,7 +1215,6 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
int state = interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
struct intel_wait wait;
unsigned long timeout_remain;
- s64 before = 0; /* Only to silence a compiler warning. */
int ret = 0;
might_sleep();
@@ -1234,12 +1233,9 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
if (*timeout == 0)
return -ETIME;
+ /* Record current time in case interrupted, or wedged */
timeout_remain = nsecs_to_jiffies_timeout(*timeout);
-
- /*
- * Record current time in case interrupted by signal, or wedged.
- */
- before = ktime_get_raw_ns();
+ *timeout += ktime_get_raw_ns();
}
trace_i915_gem_request_wait_begin(req);
@@ -1296,9 +1292,9 @@ complete:
trace_i915_gem_request_wait_end(req);
if (timeout) {
- s64 tres = *timeout - (ktime_get_raw_ns() - before);
-
- *timeout = tres < 0 ? 0 : tres;
+ *timeout -= ktime_get_raw_ns();
+ if (*timeout < 0)
+ *timeout = 0;
/*
* Apparently ktime isn't accurate enough and occasionally has a
I think this is bad, better have a local than play games with
callers storage.
It's smaller faster code :-)
You know I am normally all for that but this one I cannot approve.
Regards,
Tvrtko
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