In commit 9b6586ae9f6b ("drm/i915: Keep a global seqno per-engine"), we
moved from a global inflight counter to per-engine counters in the
hope that will be easy to run concurrently in future. However, with the
advent of the desire to move requests between engines, we do need a
global counter to preserve the semantics that no engine wraps in the
middle of a submit. (Although this semantic is now only required for gen7
semaphore support, which only supports greater-then comparisons!)
References: 9b6586ae9f6b ("drm/i915: Keep a global seqno per-engine")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_debugfs.c | 5 ++---
drivers/gpu/drm/i915/i915_gem_timeline.h | 6 ------
drivers/gpu/drm/i915/i915_request.c | 12 +++---------
drivers/gpu/drm/i915/intel_engine_cs.c | 5 ++---
4 files changed, 7 insertions(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 2f05f5262bba..547e97102b85 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1340,10 +1340,9 @@ static int i915_hangcheck_info(struct seq_file *m, void *unused)
struct rb_node *rb;
seq_printf(m, "%s:\n", engine->name);
- seq_printf(m, "\tseqno = %x [current %x, last %x], inflight %d\n",
+ seq_printf(m, "\tseqno = %x [current %x, last %x]\n",
engine->hangcheck.seqno, seqno[id],
- intel_engine_last_submit(engine),
- engine->timeline->inflight_seqnos);
+ intel_engine_last_submit(engine));
seq_printf(m, "\twaiters? %s, fake irq active? %s, stalled? %s\n",
yesno(intel_engine_has_waiter(engine)),
yesno(test_bit(engine->id,
diff --git a/drivers/gpu/drm/i915/i915_gem_timeline.h b/drivers/gpu/drm/i915/i915_gem_timeline.h
index 33e01bf6aa36..6e82119e2cd8 100644
--- a/drivers/gpu/drm/i915/i915_gem_timeline.h
+++ b/drivers/gpu/drm/i915/i915_gem_timeline.h
@@ -37,12 +37,6 @@ struct intel_timeline {
u64 fence_context;
u32 seqno;
- /**
- * Count of outstanding requests, from the time they are constructed
- * to the moment they are retired. Loosely coupled to hardware.
- */
- u32 inflight_seqnos;
-
spinlock_t lock;
/**
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index b692a9f7c357..1437538d5bfa 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -260,17 +260,14 @@ int i915_gem_set_global_seqno(struct drm_device *dev, u32 seqno)
static int reserve_engine(struct intel_engine_cs *engine)
{
struct drm_i915_private *i915 = engine->i915;
- u32 active = ++engine->timeline->inflight_seqnos;
- u32 seqno = engine->timeline->seqno;
int ret;
/* Reservation is fine until we need to wrap around */
- if (unlikely(add_overflows(seqno, active))) {
+ if (unlikely(add_overflows(engine->timeline->seqno,
+ i915->gt.active_requests + 1))) {
ret = reset_all_global_seqno(i915, 0);
- if (ret) {
- engine->timeline->inflight_seqnos--;
+ if (ret)
return ret;
- }
}
if (!i915->gt.active_requests++)
@@ -285,9 +282,6 @@ static void unreserve_engine(struct intel_engine_cs *engine)
if (!--i915->gt.active_requests)
i915_gem_park(i915);
-
- GEM_BUG_ON(!engine->timeline->inflight_seqnos);
- engine->timeline->inflight_seqnos--;
}
void i915_gem_retire_noop(struct i915_gem_active *active,
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index be608f7111f5..a55a849b81b6 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1318,12 +1318,11 @@ void intel_engine_dump(struct intel_engine_cs *engine,
if (i915_terminally_wedged(&engine->i915->gpu_error))
drm_printf(m, "*** WEDGED ***\n");
- drm_printf(m, "\tcurrent seqno %x, last %x, hangcheck %x [%d ms], inflight %d\n",
+ drm_printf(m, "\tcurrent seqno %x, last %x, hangcheck %x [%d ms]\n",
intel_engine_get_seqno(engine),
intel_engine_last_submit(engine),
engine->hangcheck.seqno,
- jiffies_to_msecs(jiffies - engine->hangcheck.action_timestamp),
- engine->timeline->inflight_seqnos);
+ jiffies_to_msecs(jiffies - engine->hangcheck.action_timestamp));
drm_printf(m, "\tReset count: %d (global %d)\n",
i915_reset_engine_count(error, engine),
i915_reset_count(error));
--
2.17.0
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