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 <[email protected]> > >--- > > 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 :-) -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
