| Message ID | 1448786893-2522-15-git-send-email-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 29/11/15 08:48, 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. > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > --- > drivers/gpu/drm/i915/i915_gem.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index 2c3e36e19cb0..871201713c73 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -1227,7 +1227,6 @@ int __i915_wait_request(struct drm_i915_gem_request *req, > int state = interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE; > DEFINE_WAIT(wait); > unsigned long timeout_remain; > - s64 before, now; > int ret; > > if (list_empty(&req->list)) > @@ -1244,13 +1243,12 @@ 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); > + *timeout += ktime_get_raw_ns(); Don't really like this one, how you use the passed in pointer to store the intermediate local state. It works etc but just feels too hacky. Regards, Tvrtko > } > > - /* Record current time in case interrupted by signal, or wedged */ > trace_i915_gem_request_wait_begin(req); > - before = ktime_get_raw_ns(); > - > if (INTEL_INFO(req->i915)->gen >= 6) > gen6_rps_boost(req->i915, rps, req->emitted_jiffies); > > @@ -1286,14 +1284,13 @@ int __i915_wait_request(struct drm_i915_gem_request *req, > } > finish_wait(&req->wait, &wait); > out: > - now = ktime_get_raw_ns(); > intel_breadcrumbs_remove_waiter(req); > trace_i915_gem_request_wait_end(req); > > if (timeout) { > - s64 tres = *timeout - (now - 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 >
On Mon, Nov 30, 2015 at 10:19:40AM +0000, Tvrtko Ursulin wrote: > > On 29/11/15 08:48, 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. > > > >Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > >--- > > drivers/gpu/drm/i915/i915_gem.c | 13 +++++-------- > > 1 file changed, 5 insertions(+), 8 deletions(-) > > > >diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > >index 2c3e36e19cb0..871201713c73 100644 > >--- a/drivers/gpu/drm/i915/i915_gem.c > >+++ b/drivers/gpu/drm/i915/i915_gem.c > >@@ -1227,7 +1227,6 @@ int __i915_wait_request(struct drm_i915_gem_request *req, > > int state = interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE; > > DEFINE_WAIT(wait); > > unsigned long timeout_remain; > >- s64 before, now; > > int ret; > > > > if (list_empty(&req->list)) > >@@ -1244,13 +1243,12 @@ 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); > >+ *timeout += ktime_get_raw_ns(); > > Don't really like this one, how you use the passed in pointer to > store the intermediate local state. > > It works etc but just feels too hacky. Bah, it's already in the CPU cache I might as well take advantage of the space. :) -Chris
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 2c3e36e19cb0..871201713c73 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1227,7 +1227,6 @@ int __i915_wait_request(struct drm_i915_gem_request *req, int state = interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE; DEFINE_WAIT(wait); unsigned long timeout_remain; - s64 before, now; int ret; if (list_empty(&req->list)) @@ -1244,13 +1243,12 @@ 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); + *timeout += ktime_get_raw_ns(); } - /* Record current time in case interrupted by signal, or wedged */ trace_i915_gem_request_wait_begin(req); - before = ktime_get_raw_ns(); - if (INTEL_INFO(req->i915)->gen >= 6) gen6_rps_boost(req->i915, rps, req->emitted_jiffies); @@ -1286,14 +1284,13 @@ int __i915_wait_request(struct drm_i915_gem_request *req, } finish_wait(&req->wait, &wait); out: - now = ktime_get_raw_ns(); intel_breadcrumbs_remove_waiter(req); trace_i915_gem_request_wait_end(req); if (timeout) { - s64 tres = *timeout - (now - 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
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. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> --- drivers/gpu/drm/i915/i915_gem.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)