On 12/09/2018 16:50, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2018-09-12 16:29:30)
/*
* The OA register config is setup through the context image. This image
* might be written to by the GPU on context switch (in particular on
@@ -1833,7 +1727,7 @@ static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
* the GPU from any submitted work.
*/
ret = i915_gem_wait_for_idle(dev_priv,
- wait_flags,
+ I915_WAIT_LOCKED,
MAX_SCHEDULE_TIMEOUT);
Wait until idle includes a wait for the gpu to switch off. At least it
does for execlists, not so clear for ringbuffer as there is no explicit
idle-event. However, that shouldn't matter as the kernel context doesn't
exist for legacy ringbuffer anyway ;) But the reload will be forced on
the next actual use.
And on top this is only called on Gen8+!
if (ret)
return ret;
@@ -1859,7 +1753,17 @@ static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
i915_gem_object_unpin_map(ce->state->obj);
}
- return ret;
+ /*
+ * Apply the configuration by doing one context restore of the edited
+ * context image.
+ */
+ rq = i915_request_alloc(engine, dev_priv->kernel_context);
By feeding a request, you ensure the reconfig is loaded again. +1 for
having it turn off when idle (and not instrument the kernel context at
all)!
Still I follow your logic that this should leave the oa config in
exactly the same state as before the patch, so
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Thanks, yeah, I am not sure excluding kernel context is possible. If I
understand the comments in i915_perf.c, and how much Lionel explained to
me, when on we want it on all the time so sampling timers are always on
regardless of context switches.
Regards,
Tvrtko
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