Quoting Mika Kuoppala (2018-05-25 13:22:55)
> Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
>
> > During suspend we want to flush out all active contexts and their
> > rendering. To do so we queue a request from the kernel's context, once
> > we know that request is done, we know the GPU is completely idle. To
> > speed up that switch bump the GPU clocks.
> >
> > Switching to the kernel context prior to idling is also used to enforce
> > a barrier before changing OA properties, and when evicting active
> > rendering from the global GTT. All cases where we do want to
> > race-to-idle.
> >
> > v2: Limit the boosting to only the switch before suspend.
> > v3: Limit it to the wait-for-idle on suspend.
> >
> > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Cc: David Weinehall <david.weinehall@xxxxxxxxxxxxxxx>
> > Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> > Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> #v1
> > Tested-by: David Weinehall <david.weinehall@xxxxxxxxxxxxxxx> #v1
> > ---
> > drivers/gpu/drm/i915/i915_gem.c | 27 +++++++++++++++++++++++++--
> > drivers/gpu/drm/i915/i915_request.h | 1 +
> > 2 files changed, 26 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> > index c93f5dcb1d82..7b5544efa0ba 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -3704,7 +3704,29 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
> >
> > static int wait_for_timeline(struct i915_timeline *tl, unsigned int flags)
> > {
> > - return i915_gem_active_wait(&tl->last_request, flags);
> > + struct i915_request *rq;
> > + long ret;
> > +
> > + rq = i915_gem_active_get_unlocked(&tl->last_request);
> > + if (!rq)
> > + return 0;
> > +
> > + /*
> > + * "Race-to-idle".
> > + *
> > + * Switching to the kernel context is often used a synchronous
> > + * step prior to idling, e.g. in suspend for flushing all
> > + * current operations to memory before sleeping. These we
> > + * want to complete as quickly as possible to avoid prolonged
> > + * stalls, so allow the gpu to boost to maximum clocks.
> > + */
> > + if (flags & I915_WAIT_FOR_IDLE_BOOST)
> > + gen6_rps_boost(rq, NULL);
> > +
> > + ret = i915_request_wait(rq, flags, MAX_SCHEDULE_TIMEOUT);
>
> I pondered about the boost flag falling through into wait.
> But they are flags on wait domain so no reason to split/limit.
Indeed,
> > #define I915_WAIT_INTERRUPTIBLE BIT(0)
> > #define I915_WAIT_LOCKED BIT(1) /* struct_mutex held, handle GPU reset */
> > #define I915_WAIT_ALL BIT(2) /* used by i915_gem_object_wait() */
> > +#define I915_WAIT_FOR_IDLE_BOOST BIT(3)
I thought was a reasonable way to share the same set of flags with
distinct regions.
Thanks for the review and discussion,
-Chris
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
