On 2/23/2022 18:03, Ceraolo Spurio, Daniele wrote:
On 2/23/2022 12:23 PM, John Harrison wrote:
On 2/22/2022 17:12, Ceraolo Spurio, Daniele wrote:
On 2/17/2022 3:52 PM, John.C.Harrison@xxxxxxxxx wrote:
From: John Harrison <John.C.Harrison@xxxxxxxxx>
The LRC descriptor was being initialised early on in the context
registration sequence. It could then be determined that the actual
registration needs to be delayed and the descriptor would be wiped
out. This is inefficient, so move the setup to later in the process
after the point of no return.
Signed-off-by: John Harrison <John.C.Harrison@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
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 0ab2d1a24bf6..aa74ec74194a 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -2153,6 +2153,8 @@ static int
__guc_action_register_context(struct intel_guc *guc,
0, loop);
}
+static void prepare_context_registration_info(struct
intel_context *ce);
+
static int register_context(struct intel_context *ce, bool loop)
{
struct intel_guc *guc = ce_to_guc(ce);
@@ -2163,6 +2165,8 @@ static int register_context(struct
intel_context *ce, bool loop)
GEM_BUG_ON(intel_context_is_child(ce));
trace_intel_context_register(ce);
+ prepare_context_registration_info(ce);
+
if (intel_context_is_parent(ce))
ret = __guc_action_register_multi_lrc(guc, ce,
ce->guc_id.id,
offset, loop);
@@ -2246,7 +2250,6 @@ static void
prepare_context_registration_info(struct intel_context *ce)
struct intel_context *child;
GEM_BUG_ON(!engine->mask);
- GEM_BUG_ON(!sched_state_is_init(ce));
/*
* Ensure LRC + CT vmas are is same region as write barrier
is done
@@ -2314,9 +2317,13 @@ static int try_context_registration(struct
intel_context *ce, bool loop)
bool context_registered;
int ret = 0;
+ GEM_BUG_ON(!sched_state_is_init(ce));
+
context_registered = ctx_id_mapped(guc, desc_idx);
- prepare_context_registration_info(ce);
+ if (context_registered)
+ clr_ctx_id_mapping(guc, desc_idx);
+ set_ctx_id_mapping(guc, desc_idx, ce);
I think we can do the clr unconditionally. Also, should we drop the
clr/set pair in prepare_context_registration_info? it shouldn't be
needed, unless I'm missing a path where we don;t pass through here.
Daniele
I don't believe so.
The point is that the context id might have changed (it got stolen,
re-used, etc. - all the state machine code below can cause aborts and
retries and such like if something is pending and the register needs
to be delayed). So we need to clear out the old mapping and add a new
one to be safe. Also, I'm not sure if it is safe to do a xa_store to
an already used entry as an update or if you are supposed to clear it
first? But that's what the code did before and I'm trying to not
change any actual behaviour here.
I was comparing with previous behavior. before this patch, we only do
the setting of the ctx_id here (inside
prepare_context_registration_info) and you're not changing any of the
abort/retry behavior, so if it was enough before it should be enough now.
Hmm, I think I must have confused myself with the intermediate steps
along the way. Yes, it looks like the clr/set in prepare is redundant by
the end.
Regarding the xa ops, we did an unconditional clear before, so it
should be ok to just do the same and have the clear and set back to
back without checking if the context ID was already in use or not.
Actually, I was thinking you meant to drop the clr completely rather
than just drop the condition. Yeah, that sounds fine.
Will post an update.
John.
Daniele
John.
/*
* The context_lookup xarray is used to determine if the
hardware
