On Thu, 27 Apr 2023 15:47:04 -0700, Umesh Nerlige Ramappa wrote: > > GPU accumulates the context runtime in a 32 bit counter - CTX_TIMESTAMP > in the context image. This value is saved/restored on context switches. > KMD accumulates these values into a 64 bit counter taking care of any > overflows as needed. This count provides the basis for client specific > busyness in the fdinfo interface. > > KMD accumulation happens just before the context is unpinned and when > context switches out. This works for execlist back-end since execlist > scheduling has visibility into context switches. With GuC mode, KMD does > not have visibility into context switches and this counter is > accumulated only when context is unpinned. Context is unpinned once the > context scheduling is successfully disabled. Disabling context > scheduling is an asynchronous operation. Also if a context is servicing > frequent requests, scheduling may never be disabled on it. > > For GuC mode, since updates to the context runtime may be delayed, add > hooks to update the context runtime in a worker thread as well as when > a user queries for it. > > Limitation: > - If a context is never switched out or runs for a long period of time, > the runtime value of CTX_TIMESTAMP may never be updated, so the > counter value may be unreliable. This patch does not support such > cases. Such support must be available from the GuC FW and it is WIP. > > This patch is an extract from previous work authored by John/Umesh here - > https://patchwork.freedesktop.org/patch/496441/?series=105085&rev=4 > > v2: (Ashutosh) > - Drop COPS_RUNTIME_ACTIVE_TOTAL > - s/guc_context_update_clks/__guc_context_update_stats > - Pin context before accessing in guc_timestamp_ping > - In guc_context_unpin, use spinlock to serialize access to runtime stats LGTM now: Reviewed-by: Ashutosh Dixit <ashutosh.dixit@xxxxxxxxx> I have made a few notes for myself below. > > Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx> > Co-developed-by: John Harrison <John.C.Harrison@xxxxxxxxx> > Signed-off-by: John Harrison <John.C.Harrison@xxxxxxxxx> > --- > drivers/gpu/drm/i915/gt/intel_context.c | 5 ++- > drivers/gpu/drm/i915/gt/intel_context.h | 2 +- > drivers/gpu/drm/i915/gt/intel_context_types.h | 2 ++ > .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 31 +++++++++++++++++++ > 4 files changed, 38 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c > index 2aa63ec521b8..a53b26178f0a 100644 > --- a/drivers/gpu/drm/i915/gt/intel_context.c > +++ b/drivers/gpu/drm/i915/gt/intel_context.c > @@ -578,10 +578,13 @@ void intel_context_bind_parent_child(struct intel_context *parent, > child->parallel.parent = parent; > } > > -u64 intel_context_get_total_runtime_ns(const struct intel_context *ce) > +u64 intel_context_get_total_runtime_ns(struct intel_context *ce) > { > u64 total, active; > > + if (ce->ops->update_stats) > + ce->ops->update_stats(ce); This is indeed called from atomic context due to rcu_read_lock in show_client_class, so we can't sleep in update_stats (and we are not due to use of intel_context_pin_if_active). Because we are already updating stats from guc_timestamp_ping, we could have skipped updating them again from here without losing too much accuracy but it's fine. > + > total = ce->stats.runtime.total; > if (ce->ops->flags & COPS_RUNTIME_CYCLES) > total *= ce->engine->gt->clock_period_ns; > diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h > index 48f888c3da08..43ed92f8dc83 100644 > --- a/drivers/gpu/drm/i915/gt/intel_context.h > +++ b/drivers/gpu/drm/i915/gt/intel_context.h > @@ -375,7 +375,7 @@ intel_context_clear_nopreempt(struct intel_context *ce) > clear_bit(CONTEXT_NOPREEMPT, &ce->flags); > } > > -u64 intel_context_get_total_runtime_ns(const struct intel_context *ce); > +u64 intel_context_get_total_runtime_ns(struct intel_context *ce); > u64 intel_context_get_avg_runtime_ns(struct intel_context *ce); > > static inline u64 intel_context_clock(void) > diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h > index e36670f2e626..aceaac28a33e 100644 > --- a/drivers/gpu/drm/i915/gt/intel_context_types.h > +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h > @@ -58,6 +58,8 @@ struct intel_context_ops { > > void (*sched_disable)(struct intel_context *ce); > > + void (*update_stats)(struct intel_context *ce); > + > void (*reset)(struct intel_context *ce); > void (*destroy)(struct kref *kref); > > 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 ee3e8352637f..c869ddc73e69 100644 > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c > @@ -1402,13 +1402,34 @@ static void __update_guc_busyness_stats(struct intel_guc *guc) > spin_unlock_irqrestore(&guc->timestamp.lock, flags); > } > > +static void __guc_context_update_stats(struct intel_context *ce) > +{ > + struct intel_guc *guc = ce_to_guc(ce); > + unsigned long flags; > + > + spin_lock_irqsave(&guc->timestamp.lock, flags); > + lrc_update_runtime(ce); > + spin_unlock_irqrestore(&guc->timestamp.lock, flags); > +} > + > +static void guc_context_update_stats(struct intel_context *ce) > +{ > + if (!intel_context_pin_if_active(ce)) Correct, all we need here is intel_context_pin_if_active. If the context is not pinned we updated stats when we unpinned. > + return; > + > + __guc_context_update_stats(ce); > + intel_context_unpin(ce); > +} > + > static void guc_timestamp_ping(struct work_struct *wrk) > { > struct intel_guc *guc = container_of(wrk, typeof(*guc), > timestamp.work.work); > struct intel_uc *uc = container_of(guc, typeof(*uc), guc); > struct intel_gt *gt = guc_to_gt(guc); > + struct intel_context *ce; > intel_wakeref_t wakeref; > + unsigned long index; > int srcu, ret; > > /* > @@ -1424,6 +1445,10 @@ static void guc_timestamp_ping(struct work_struct *wrk) > with_intel_runtime_pm(>->i915->runtime_pm, wakeref) > __update_guc_busyness_stats(guc); > > + /* adjust context stats for overflow */ > + xa_for_each(&guc->context_lookup, index, ce) > + guc_context_update_stats(ce); This helps prevent overflow if the context switched out (which updated the runtime in the context image) but was not not unpinned. > + > intel_gt_reset_unlock(gt, srcu); > > guc_enable_busyness_worker(guc); > @@ -2774,6 +2799,7 @@ static void guc_context_unpin(struct intel_context *ce) > { > struct intel_guc *guc = ce_to_guc(ce); > > + __guc_context_update_stats(ce); Correct, cannot call intel_context_unpin (from guc_context_update_stats) since this function is called from intel_context_unpin. > unpin_guc_id(guc, ce); > lrc_unpin(ce); > > @@ -3455,6 +3481,7 @@ static void remove_from_context(struct i915_request *rq) > } > > static const struct intel_context_ops guc_context_ops = { > + .flags = COPS_RUNTIME_CYCLES, > .alloc = guc_context_alloc, > > .close = guc_context_close, > @@ -3473,6 +3500,8 @@ static const struct intel_context_ops guc_context_ops = { > > .sched_disable = guc_context_sched_disable, > > + .update_stats = guc_context_update_stats, > + > .reset = lrc_reset, > .destroy = guc_context_destroy, > > @@ -3728,6 +3757,7 @@ static int guc_virtual_context_alloc(struct intel_context *ce) > } > > static const struct intel_context_ops virtual_guc_context_ops = { > + .flags = COPS_RUNTIME_CYCLES, > .alloc = guc_virtual_context_alloc, > > .close = guc_context_close, > @@ -3745,6 +3775,7 @@ static const struct intel_context_ops virtual_guc_context_ops = { > .exit = guc_virtual_context_exit, > > .sched_disable = guc_context_sched_disable, > + .update_stats = guc_context_update_stats, The approach should also work for virtual engines. > > .destroy = guc_context_destroy, > > -- > 2.36.1 > Thanks. -- Ashutosh
