We want to expose the parameters for controlling how long it takes for
us to notice and park the GPU after a stream of requests in order to try
and tune the optimal power-efficiency vs latency of a mostly idle system.
v2: retire_work has two scheduling points, update them both
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/Kconfig.profile | 23 +++++++++++++++++++++++
drivers/gpu/drm/i915/i915_gem.c | 8 +++++---
drivers/gpu/drm/i915/i915_gem.h | 13 +++++++++++++
3 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/Kconfig.profile b/drivers/gpu/drm/i915/Kconfig.profile
index 8a230eeb98df..63cb744d920d 100644
--- a/drivers/gpu/drm/i915/Kconfig.profile
+++ b/drivers/gpu/drm/i915/Kconfig.profile
@@ -24,3 +24,26 @@ config DRM_I915_SPIN_REQUEST_CS
spin prior to sleeping again.
May be 0 to disable spinning after being woken.
+
+config DRM_I915_GEM_RETIRE_DELAY
+ int
+ default 1000 # milliseconds
+ help
+ We maintain a background job whose purpose is to keep cleaning up
+ after userspace, and may be the first to spot an idle system. This
+ parameter determines the interval between execution of the worker.
+
+ To reduce the number of timer wakeups, large delays (of greater than
+ a second) are rounded to the next walltime second to allow coalescing
+ of multiple system timers into a single wakeup.
+
+config DRM_I915_GEM_PARK_DELAY
+ int
+ default 100 # milliseconds
+ help
+ Before parking the engines and the GPU after the final request is
+ retired, we may wait for a small delay to reduce the frequecy of
+ having to park/unpark and so the latency in executing a new request.
+
+ May be 0 to immediately start parking the engines after the last
+ request.
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 460f256114f7..5b538a92631d 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -192,7 +192,9 @@ void i915_gem_park(struct drm_i915_private *i915)
return;
/* Defer the actual call to __i915_gem_park() to prevent ping-pongs */
- mod_delayed_work(i915->wq, &i915->gt.idle_work, msecs_to_jiffies(100));
+ mod_delayed_work(i915->wq,
+ &i915->gt.idle_work,
+ msecs_to_jiffies(CONFIG_DRM_I915_GEM_PARK_DELAY));
}
void i915_gem_unpark(struct drm_i915_private *i915)
@@ -236,7 +238,7 @@ void i915_gem_unpark(struct drm_i915_private *i915)
queue_delayed_work(i915->wq,
&i915->gt.retire_work,
- round_jiffies_up_relative(HZ));
+ i915_gem_retire_delay());
}
int
@@ -3466,7 +3468,7 @@ i915_gem_retire_work_handler(struct work_struct *work)
if (READ_ONCE(dev_priv->gt.awake))
queue_delayed_work(dev_priv->wq,
&dev_priv->gt.retire_work,
- round_jiffies_up_relative(HZ));
+ i915_gem_retire_delay());
}
static void shrink_caches(struct drm_i915_private *i915)
diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
index e46592956872..c6b4971435dc 100644
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -27,6 +27,8 @@
#include <linux/bug.h>
#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/timer.h>
struct drm_i915_private;
@@ -76,6 +78,17 @@ struct drm_i915_private;
void i915_gem_park(struct drm_i915_private *i915);
void i915_gem_unpark(struct drm_i915_private *i915);
+static inline unsigned long i915_gem_retire_delay(void)
+{
+ const unsigned long delay =
+ msecs_to_jiffies(CONFIG_DRM_I915_GEM_RETIRE_DELAY);
+
+ if (CONFIG_DRM_I915_GEM_RETIRE_DELAY >= 1000)
+ return round_jiffies_up_relative(delay);
+ else
+ return delay;
+}
+
static inline void __tasklet_disable_sync_once(struct tasklet_struct *t)
{
if (atomic_inc_return(&t->count) == 1)
--
2.18.0
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