[PATCH] drm/i915: Use locked access to ctx->engines in set_priority
Daniel Vetter
daniel.vetter at ffwll.ch
Tue Aug 10 13:05:23 UTC 2021
This essentially reverts
commit 89ff76bf9b3b0b86e6bbe344bd6378d8661303fc
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date: Thu Apr 2 13:42:18 2020 +0100
drm/i915/gem: Utilize rcu iteration of context engines
Note that the other use of __context_engines_await have disappeard in
the following commits:
ccbc1b97948a ("drm/i915/gem: Don't allow changing the VM on running contexts (v4)")
c7a71fc8ee04 ("drm/i915: Drop getparam support for I915_CONTEXT_PARAM_ENGINES")
4a766ae40ec8 ("drm/i915: Drop the CONTEXT_CLONE API (v2)")
None of these have any business to optimize their engine lookup with
rcu, unless extremely convincing benchmark data and a solid analysis
why we can't make that workload (whatever it is that does) faster with
a proper design fix.
Also since there's only one caller of context_apply_all left and it's
really just a loop, inline it and then inline the lopp body too. This
is how all other callers that take the engine lock loop over engines,
it's much simpler.
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Jason Ekstrand <jason at jlekstrand.net>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Matthew Brost <matthew.brost at intel.com>
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 72 ++++-----------------
1 file changed, 14 insertions(+), 58 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index dbaeb924a437..fd169cf2f75a 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -1284,49 +1284,6 @@ static int __context_set_persistence(struct i915_gem_context *ctx, bool state)
return 0;
}
-static inline struct i915_gem_engines *
-__context_engines_await(const struct i915_gem_context *ctx,
- bool *user_engines)
-{
- struct i915_gem_engines *engines;
-
- rcu_read_lock();
- do {
- engines = rcu_dereference(ctx->engines);
- GEM_BUG_ON(!engines);
-
- if (user_engines)
- *user_engines = i915_gem_context_user_engines(ctx);
-
- /* successful await => strong mb */
- if (unlikely(!i915_sw_fence_await(&engines->fence)))
- continue;
-
- if (likely(engines == rcu_access_pointer(ctx->engines)))
- break;
-
- i915_sw_fence_complete(&engines->fence);
- } while (1);
- rcu_read_unlock();
-
- return engines;
-}
-
-static void
-context_apply_all(struct i915_gem_context *ctx,
- void (*fn)(struct intel_context *ce, void *data),
- void *data)
-{
- struct i915_gem_engines_iter it;
- struct i915_gem_engines *e;
- struct intel_context *ce;
-
- e = __context_engines_await(ctx, NULL);
- for_each_gem_engine(ce, e, it)
- fn(ce, data);
- i915_sw_fence_complete(&e->fence);
-}
-
static struct i915_gem_context *
i915_gem_create_context(struct drm_i915_private *i915,
const struct i915_gem_proto_context *pc)
@@ -1776,23 +1733,11 @@ set_persistence(struct i915_gem_context *ctx,
return __context_set_persistence(ctx, args->value);
}
-static void __apply_priority(struct intel_context *ce, void *arg)
-{
- struct i915_gem_context *ctx = arg;
-
- if (!intel_engine_has_timeslices(ce->engine))
- return;
-
- if (ctx->sched.priority >= I915_PRIORITY_NORMAL &&
- intel_engine_has_semaphores(ce->engine))
- intel_context_set_use_semaphores(ce);
- else
- intel_context_clear_use_semaphores(ce);
-}
-
static int set_priority(struct i915_gem_context *ctx,
const struct drm_i915_gem_context_param *args)
{
+ struct i915_gem_engines_iter it;
+ struct intel_context *ce;
int err;
err = validate_priority(ctx->i915, args);
@@ -1800,7 +1745,18 @@ static int set_priority(struct i915_gem_context *ctx,
return err;
ctx->sched.priority = args->value;
- context_apply_all(ctx, __apply_priority, ctx);
+
+ for_each_gem_engine(ce, i915_gem_context_lock_engines(ctx), it) {
+ if (!intel_engine_has_timeslices(ce->engine))
+ continue;
+
+ if (ctx->sched.priority >= I915_PRIORITY_NORMAL &&
+ intel_engine_has_semaphores(ce->engine))
+ intel_context_set_use_semaphores(ce);
+ else
+ intel_context_clear_use_semaphores(ce);
+ }
+ i915_gem_context_unlock_engines(ctx);
return 0;
}
--
2.32.0
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