On 26/03/2018 12:50, Chris Wilson wrote:
EGL_NV_realtime_priority?
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_gem_context.c | 22 ++++++++++++++++++++++
drivers/gpu/drm/i915/i915_gem_context.h | 13 +++++++++++++
drivers/gpu/drm/i915/i915_request.c | 8 ++++++--
drivers/gpu/drm/i915/intel_lrc.c | 2 +-
include/uapi/drm/i915_drm.h | 12 ++++++++++++
5 files changed, 54 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c
b/drivers/gpu/drm/i915/i915_gem_context.c
index 5cfac0255758..dfb0a2b698c3 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -749,6 +749,15 @@ int i915_gem_context_getparam_ioctl(struct drm_device
*dev, void *data,
case I915_CONTEXT_PARAM_PRIORITY:
args->value = ctx->priority;
break;
+ case I915_CONTEXT_PARAM_PREEMPT_TIMEOUT:
+ if (!(to_i915(dev)->caps.scheduler &
I915_SCHEDULER_CAP_PREEMPTION))
+ ret = -ENODEV;
+ else if (args->size)
+ ret = -EINVAL;
+ else
+ args->value = ctx->preempt_timeout;
+ break;
+
default:
ret = -EINVAL;
break;
@@ -824,6 +833,19 @@ int i915_gem_context_setparam_ioctl(struct drm_device
*dev, void *data,
}
break;
+ case I915_CONTEXT_PARAM_PREEMPT_TIMEOUT:
+ if (args->size)
+ ret = -EINVAL;
+ else if (args->value >= NSEC_PER_SEC)
+ ret = -EINVAL;
+ else if (!(to_i915(dev)->caps.scheduler &
I915_SCHEDULER_CAP_PREEMPTION))
+ ret = -ENODEV;
+ else if (args->value && !capable(CAP_SYS_ADMIN))
+ ret = -EPERM;
+ else
+ ctx->preempt_timeout = args->value;
+ break;
+
default:
ret = -EINVAL;
break;
diff --git a/drivers/gpu/drm/i915/i915_gem_context.h
b/drivers/gpu/drm/i915/i915_gem_context.h
index 7854262ddfd9..74d4cadd729e 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.h
+++ b/drivers/gpu/drm/i915/i915_gem_context.h
@@ -150,6 +150,19 @@ struct i915_gem_context {
*/
int priority;
+ /**
+ * @preempt_timeout: QoS guarantee for the high priority context
+ *
+ * Some clients need a guarantee that they will start executing
+ * within a certain window, even at the expense of others. This entails
+ * that if a preemption request is not honoured by the active context
+ * within the timeout, we will reset the GPU to evict the hog and
+ * run the high priority context instead.
+ *
+ * Timeout is stored in nanoseconds; exclusive max of 1s.
Why did you think we would want to limit it to 1s?
+ */
+ u32 preempt_timeout;
+
/** ggtt_offset_bias: placement restriction for context objects */
u32 ggtt_offset_bias;
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 9d8dcebd9649..2cd4ea75d127 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1101,8 +1101,12 @@ void __i915_request_add(struct i915_request *request,
bool flush_caches)
* run at the earliest possible convenience.
*/
rcu_read_lock();
- if (engine->schedule)
- engine->schedule(request, request->ctx->priority, 0);
+ if (engine->schedule) {
+ unsigned int timeout = request->ctx->preempt_timeout;
+ int priority = request->ctx->priority;
+
+ engine->schedule(request, priority, timeout);
+ }
rcu_read_unlock();
local_bh_disable();
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index e266657851e1..e782a621b40b 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1148,7 +1148,7 @@ static void execlists_submit_request(struct i915_request
*request)
spin_lock_irqsave(&engine->timeline->lock, flags);
queue_request(engine, &request->priotree, rq_prio(request));
- submit_queue(engine, rq_prio(request), 0);
+ submit_queue(engine, rq_prio(request), request->ctx->preempt_timeout);
GEM_BUG_ON(!engine->execlists.first);
GEM_BUG_ON(list_empty(&request->priotree.link));
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 7f5634ce8e88..6f10bbe90304 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1456,6 +1456,18 @@ struct drm_i915_gem_context_param {
#define I915_CONTEXT_MAX_USER_PRIORITY 1023 /* inclusive */
#define I915_CONTEXT_DEFAULT_PRIORITY 0
#define I915_CONTEXT_MIN_USER_PRIORITY -1023 /* inclusive */
+
+/*
+ * I915_CONTEXT_PARAM_PREEMPT_TIMEOUT:
+ *
+ * Preemption timeout give in nanoseconds.
+ *
+ * Only allowed for privileged clients (CAP_SYS_ADMIN), this property allows
+ * the preempting context to kick out a GPU hog using a GPU reset if they do
+ * not honour the preemption request in time.
+ */
+#define I915_CONTEXT_PARAM_PREEMPT_TIMEOUT 0x7
+
Since I expressed a concern on the "force preemption" naming in the
other thread, I feel obliged to say that I am OK with PREEMPT_TIMEOUT. :)
Regards,
Tvrtko
__u64 value;
};
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