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drm/i915: Use locked access to ctx->engines in set_priority

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This essentially reverts

commit 89ff76bf9b3b0b86e6bbe344bd6378d8661303fc
Author: Chris Wilson <chris@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.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210810130523.1972031-1-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter 2021-08-10 15:05:23 +02:00
parent d16de9a25b
commit b97090575e
1 changed files with 14 additions and 58 deletions
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72
drivers/gpu/drm/i915/gem/i915_gem_context.c
View File

@ -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;
}