[Intel-gfx] [RFC 4/4] drm/i915: Remove trylock-looping from the shrinker
Tvrtko Ursulin
tvrtko.ursulin at linux.intel.com
Thu Jan 3 13:10:21 UTC 2019
On 03/01/2019 12:56, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-01-03 12:23:29)
>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>
>> In a patch named "drm/i915: Return immediately if trylock fails for
>> direct-reclaim" Chris Wilson implicitly suggests it is safe to use a plain
>> mutex_lock instead of trylock on the I915_SHRINK_ACTIVE code paths.
>>
>> Explore this to see how the lockdep traces will look.
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>> Cc: Chris Wilson <chris at chris-wilson.co.uk>
>> ---
>> drivers/gpu/drm/i915/i915_gem_shrinker.c | 11 ++---------
>> 1 file changed, 2 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
>> index 97deec775f40..2d4a54851c0a 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
>> +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
>> @@ -47,15 +47,8 @@ shrinker_lock(struct drm_i915_private *i915, unsigned int flags, bool *unlock)
>> case MUTEX_TRYLOCK_FAILED:
>> *unlock = false;
>> if (flags & I915_SHRINK_ACTIVE) {
>> - preempt_disable();
>> - do {
>> - cpu_relax();
>> - if (mutex_trylock(&i915->drm.struct_mutex)) {
>> - *unlock = true;
>> - break;
>> - }
>> - } while (!need_resched());
>> - preempt_enable();
>> + mutex_lock(&i915->drm.struct_mutex);
>
> You seemed to have lost some annotation here.
I deliberately omitted mutex_lock_nested from this series to avoid
hiding any potential lockdep issues. If there won't be any hit then we
really need to improve on the test coverage.
Regards,
Tvrtko
More information about the Intel-gfx
mailing list