On Wed, Jun 15, 2022 at 08:08:40AM +0100, Tvrtko Ursulin wrote:
On 14/06/2022 17:32, Umesh Nerlige Ramappa wrote:
On Tue, Jun 14, 2022 at 02:30:42PM +0100, Tvrtko Ursulin wrote:
On 14/06/2022 01:46, Nerlige Ramappa, Umesh wrote:
From: John Harrison <John.C.Harrison@xxxxxxxxx>
GuC provides engine_id and last_switch_in ticks for an active
context in the
pphwsp. The context image provides a 32 bit total ticks which is
the accumulated
by the context (a.k.a. context[CTX_TIMESTAMP]). This information
is used to
calculate the context busyness as follows:
If the engine_id is valid, then busyness is the sum of
accumulated total ticks
and active ticks. Active ticks is calculated with current gt
time as reference.
If engine_id is invalid, busyness is equal to accumulated total ticks.
Since KMD (CPU) retrieves busyness data from 2 sources - GPU and GuC, a
potential race was highlighted in an earlier review that can
lead to double
accounting of busyness. While the solution to this is a wip,
busyness is still
usable for platforms running GuC submission.
Signed-off-by: John Harrison <John.C.Harrison@xxxxxxxxx>
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_context.c | 11 +++-
drivers/gpu/drm/i915/gt/intel_context.h | 6 +-
drivers/gpu/drm/i915/gt/intel_context_types.h | 3 +
drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h | 5 ++
.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 55 ++++++++++++++++++-
drivers/gpu/drm/i915/i915_drm_client.c | 6 +-
6 files changed, 75 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c
b/drivers/gpu/drm/i915/gt/intel_context.c
index 4070cb5711d8..a49f313db911 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -576,16 +576,23 @@ 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);
+
total = ce->stats.runtime.total;
if (ce->ops->flags & COPS_RUNTIME_CYCLES)
total *= ce->engine->gt->clock_period_ns;
active = READ_ONCE(ce->stats.active);
- if (active)
+ /*
+ * GuC backend returns the actual time the context was
active, so skip
+ * the calculation here for GuC.
+ */
+ if (active && !intel_engine_uses_guc(ce->engine))
What is the point of looking at ce->stats.active in GuC mode? I
see that guc_context_update_stats/__guc_context_update_clks
touches it, but I can't spot that there is a purpose to it. This
is the only conditional reading it but it is short-circuited in
GuC case.
Also, since a GuC only vfunc (update_stats) has been added, I
wonder why not just fork the whole runtime query
(ce->get_total_runtime_ns). I think that would end up cleaner.
active = intel_context_clock() - active;
return total + active;
In case of GuC the active is used directly here since the active
updated in update_stats is equal to the active time of the context
already. I will look into separate vfunc.
Ah right, I misread something. But yes, I think a separate vfunc will
look cleaner. Another option (instead of vfunc) is a similar flag to
control the express the flavour of active?
Flag does sound simpler. The guc context ops can have something like
COPS_RUNTIME_ACTIVE_TOTAL that means total active time.
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h
b/drivers/gpu/drm/i915/gt/intel_context.h
index b7d3214d2cdd..5fc7c19ab29b 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -56,7 +56,7 @@ static inline bool
intel_context_is_parent(struct intel_context *ce)
return !!ce->parallel.number_children;
}
snip
+static void __guc_context_update_clks(struct intel_context *ce)
+{
+ struct intel_guc *guc = ce_to_guc(ce);
+ struct intel_gt *gt = ce->engine->gt;
+ u32 *pphwsp, last_switch, engine_id;
+ u64 start_gt_clk = 0, active = 0;
No need to init these two.
+ unsigned long flags;
+ ktime_t unused;
+
+ spin_lock_irqsave(&guc->timestamp.lock, flags);
+
+ pphwsp = ((void *)ce->lrc_reg_state) - LRC_STATE_OFFSET;
+ last_switch = READ_ONCE(pphwsp[PPHWSP_GUC_CONTEXT_USAGE_STAMP_LO]);
+ engine_id = READ_ONCE(pphwsp[PPHWSP_GUC_CONTEXT_USAGE_ENGINE_ID]);
+
+ guc_update_pm_timestamp(guc, &unused);
+
+ if (engine_id != 0xffffffff && last_switch) {
+ start_gt_clk = READ_ONCE(ce->stats.runtime.start_gt_clk);
+ __extend_last_switch(guc, &start_gt_clk, last_switch);
+ active = intel_gt_clock_interval_to_ns(gt,
guc->timestamp.gt_stamp - start_gt_clk);
+ WRITE_ONCE(ce->stats.runtime.start_gt_clk, start_gt_clk);
+ WRITE_ONCE(ce->stats.active, active);
+ } else {
+ lrc_update_runtime(ce);
Why is this called from here? Presumably it was called already
from guc_context_unpin if here code things context is not active.
Or will be called shortly, once context save is done.
guc_context_unpin is only called in the path of ce->sched_disable.
The sched_disable is implemented in GuC (H2G message). Once the
corresponding G2H response is received, the context is actually
unpinned, eventually calling guc_context_unpin. Also the context may
not necessarily be disabled after each context exit.
So if I understand correctly, lrc runtime is only updated if someone
is reading the busyness and not as part of normal context state
transitions?
If you mean context_in/out events (like csb interrupts), only GuC can
see those events. KMD has no visibility into that. These 3 paths call
lrc_update_runtime.
user query: (engine_id != 0xffffffff && last_switch) translates to GuC
being within context_in and context_out events, so updating it outside
of this window is one way to report the correct busyness.
worker: guc_timestamp_ping() also updates context stats (infrequently)
for all contexts primarily to take care of overflows.
context unpin: Existing code calls lrc_update_runtime only when
unpinning the context which takes care of accumulating busyness when
requests are retired.
Thanks,
Umesh
Regards,
Tvrtko
