On Mon, Oct 04, 2021 at 03:36:49PM +0100, Tvrtko Ursulin wrote: > From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > > Introduce the concept of context nice value which matches the process > nice. > > We do this by extending the struct i915_sched_attr and add a helper > (i915_sched_attr_priority) to be used to convert to effective priority > when used by backend code and for priority sorting. > > Context nice is then inherited from the process which creates the GEM > context and utilised secondary to context priority, only when the latter > has been left at the default setting, in order to avoid disturbing any > application made choices of low and high (batch processing and maybe > latency sensitive compositing). In those cases nice value adjusts the > effective priority in the narrow band of -19 to +20 around > I915_CONTEXT_DEFAULT_PRIORITY. > > This means that in theory userspace using the context priority uapi > directly has a wider range of possible adjustments (thought to be > beneficial), but in practice that only applies to execlists platforms. > With GuC there are only three priority buckets (less than zero is low > priority, zero is normal and greater than zero is high) which therefore > interact as expected with the nice adjustment. It makes the question of > should the nice be a sub-range of GEM priorities, or stretched across the > whole, a moot one. > Opps, sorry for the double reply to this patch - for some reason I thinking the below comment would be on the next patch. The GuC + DRM scheduler actually has 4 priorities with the highest reserved for the KMD, so 3 user levels which is what I think you mean. So how would this work with only 3 levels? The nice value can move a normal priority value to either low or high, right? Normal to low seems fine but would moving to high be an issue? I thought a high level was reserved for elevated user processes (e.g. a root user or a compositor)? Would it be ok for a non-elevated user process to be the same priority as an elevated process? Matt > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > --- > drivers/gpu/drm/i915/gem/i915_gem_context.c | 1 + > .../gpu/drm/i915/gt/intel_execlists_submission.c | 4 ++-- > drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 2 +- > drivers/gpu/drm/i915/i915_request.c | 2 +- > drivers/gpu/drm/i915/i915_request.h | 5 +++++ > drivers/gpu/drm/i915/i915_scheduler.c | 12 ++++++++---- > drivers/gpu/drm/i915/i915_scheduler.h | 14 ++++++++++++++ > drivers/gpu/drm/i915/i915_scheduler_types.h | 8 ++++++++ > 8 files changed, 40 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c > index 8d4d687ab1d0..fed0733cb652 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c > @@ -257,6 +257,7 @@ proto_context_create(struct drm_i915_private *i915, unsigned int flags) > if (i915->params.enable_hangcheck) > pc->user_flags |= BIT(UCONTEXT_PERSISTENCE); > pc->sched.priority = I915_PRIORITY_NORMAL; > + pc->sched.nice = task_nice(current); > > if (flags & I915_CONTEXT_CREATE_FLAGS_SINGLE_TIMELINE) { > if (!HAS_EXECLISTS(i915)) { > diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c > index e91d803a6453..1a02c65823a7 100644 > --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c > +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c > @@ -250,7 +250,7 @@ static struct i915_priolist *to_priolist(struct rb_node *rb) > > static int rq_prio(const struct i915_request *rq) > { > - return READ_ONCE(rq->sched.attr.priority); > + return i915_request_priority(rq); > } > > static int effective_prio(const struct i915_request *rq) > @@ -3221,8 +3221,8 @@ static void kick_execlists(const struct i915_request *rq, > { > struct intel_engine_cs *engine = rq->engine; > struct i915_sched_engine *sched_engine = engine->sched_engine; > + const int prio = i915_sched_attr_priority(attr); > const struct i915_request *inflight; > - const int prio = attr->priority; > > /* > * We only need to kick the tasklet once for the high priority > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > index b5883a4365ca..f258607685a2 100644 > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > @@ -2417,7 +2417,7 @@ static void guc_bump_inflight_request_prio(struct i915_request *rq, > const struct i915_sched_attr *attr) > { > struct intel_context *ce = rq->context; > - const int prio = attr->priority; > + const int prio = i915_sched_attr_priority(attr); > u8 new_guc_prio = map_i915_prio_to_guc_prio(prio); > > /* Short circuit function */ > diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c > index 79da5eca60af..a8c6f3a64895 100644 > --- a/drivers/gpu/drm/i915/i915_request.c > +++ b/drivers/gpu/drm/i915/i915_request.c > @@ -1930,7 +1930,7 @@ static int print_sched_attr(const struct i915_sched_attr *attr, > return x; > > x += snprintf(buf + x, len - x, > - " prio=%d", attr->priority); > + " prio=%d nice=%d", attr->priority, attr->nice); > > return x; > } > diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h > index 7bd9ed20623e..c2c4c344837e 100644 > --- a/drivers/gpu/drm/i915/i915_request.h > +++ b/drivers/gpu/drm/i915/i915_request.h > @@ -399,6 +399,11 @@ long i915_request_wait(struct i915_request *rq, > #define I915_WAIT_PRIORITY BIT(1) /* small priority bump for the request */ > #define I915_WAIT_ALL BIT(2) /* used by i915_gem_object_wait() */ > > +static inline int i915_request_priority(const struct i915_request *rq) > +{ > + return i915_sched_attr_priority(&rq->sched.attr); > +} > + > void i915_request_show(struct drm_printer *m, > const struct i915_request *rq, > const char *prefix, > diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c > index 534bab99fcdc..e75793e36454 100644 > --- a/drivers/gpu/drm/i915/i915_scheduler.c > +++ b/drivers/gpu/drm/i915/i915_scheduler.c > @@ -155,7 +155,9 @@ lock_sched_engine(struct i915_sched_node *node, > static void __i915_schedule(struct i915_sched_node *node, > const struct i915_sched_attr *attr) > { > - const int prio = max(attr->priority, node->attr.priority); > + const int prio = > + max(i915_sched_attr_priority(attr), > + i915_sched_attr_priority(&node->attr)); > struct i915_sched_engine *sched_engine; > struct i915_dependency *dep, *p; > struct i915_dependency stack; > @@ -209,7 +211,7 @@ static void __i915_schedule(struct i915_sched_node *node, > if (node_signaled(p->signaler)) > continue; > > - if (prio > READ_ONCE(p->signaler->attr.priority)) > + if (prio > i915_sched_attr_priority(&p->signaler->attr)) > list_move_tail(&p->dfs_link, &dfs); > } > } > @@ -247,7 +249,8 @@ static void __i915_schedule(struct i915_sched_node *node, > lockdep_assert_held(&sched_engine->lock); > > /* Recheck after acquiring the engine->timeline.lock */ > - if (prio <= node->attr.priority || node_signaled(node)) > + if (prio <= i915_sched_attr_priority(&node->attr) || > + node_signaled(node)) > continue; > > GEM_BUG_ON(node_to_request(node)->engine->sched_engine != > @@ -257,7 +260,7 @@ static void __i915_schedule(struct i915_sched_node *node, > if (sched_engine->bump_inflight_request_prio) > sched_engine->bump_inflight_request_prio(from, attr); > > - WRITE_ONCE(node->attr.priority, prio); > + WRITE_ONCE(node->attr, *attr); > > /* > * Once the request is ready, it will be placed into the > @@ -305,6 +308,7 @@ void i915_sched_node_init(struct i915_sched_node *node) > void i915_sched_node_reinit(struct i915_sched_node *node) > { > node->attr.priority = I915_PRIORITY_INVALID; > + node->attr.nice = 0; > node->semaphores = 0; > node->flags = 0; > > diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h > index 0b9b86af6c7f..75ccc9f55d14 100644 > --- a/drivers/gpu/drm/i915/i915_scheduler.h > +++ b/drivers/gpu/drm/i915/i915_scheduler.h > @@ -38,6 +38,20 @@ void i915_sched_node_fini(struct i915_sched_node *node); > void i915_schedule(struct i915_request *request, > const struct i915_sched_attr *attr); > > +static inline int i915_sched_attr_priority(const struct i915_sched_attr *attr) > +{ > + int prio = attr->priority; > + > + /* > + * Only allow I915_CONTEXT_DEFAULT_PRIORITY to be affected by the > + * nice setting. > + */ > + if (!prio) > + prio = -attr->nice; > + > + return prio; > +} > + > struct list_head * > i915_sched_lookup_priolist(struct i915_sched_engine *sched_engine, int prio); > > diff --git a/drivers/gpu/drm/i915/i915_scheduler_types.h b/drivers/gpu/drm/i915/i915_scheduler_types.h > index 24b9ac1c2ce2..159237aa7609 100644 > --- a/drivers/gpu/drm/i915/i915_scheduler_types.h > +++ b/drivers/gpu/drm/i915/i915_scheduler_types.h > @@ -29,6 +29,14 @@ struct i915_sched_attr { > * The &drm_i915_private.kernel_context is assigned the lowest priority. > */ > int priority; > + > + /** > + * @nice: context nice level > + * > + * Nice level follows the CPU scheduler nice value as set for the > + * process owning the GPU context. > + */ > + int nice; > }; > > /* > -- > 2.30.2 >