On 3/9/22 04:12, Rob Clark wrote:
>> +static unsigned long
>> +virtio_gpu_gem_shrinker_count_objects(struct shrinker *shrinker,
>> + struct shrink_control *sc)
>> +{
>> + struct drm_gem_shmem_object *shmem;
>> + struct virtio_gpu_device *vgdev;
>> + unsigned long count = 0;
>> + bool empty = true;
>> +
>> + vgdev = container_of(shrinker, struct virtio_gpu_device,
>> + vgshrinker.shrinker);
>> +
>> + if (!mutex_trylock(&vgdev->mm_lock))
>> + return 0;
> One bit of advice from previously dealing with shrinker and heavy
> memory pressure situations (turns out 4GB chromebooks can be pretty
> much under *constant* memory pressure):
>
> You *really* want to make shrinker->count_objects lockless.. and
> minimize the lock contention on shrinker->scan_objects (ie. The
> problem is you can end up with shrinking going on on all CPU cores in
> parallel, you want to not funnel that thru one lock as much as
> possible.
>
> See in particular:
>
> 25ed38b3ed26 ("drm/msm: Drop mm_lock in scan loop")
> cc8a4d5a1bd8 ("drm/msm: Avoid mutex in shrinker_count()")
Thank you, I'll take that into account for v2.
