Re: [PATCH v2] gpu: drm: amd: amdkfd: Remove create_workqueue()

On Thu, May 26, 2016 at 10:37 PM, Bhaktipriya Shridhar bhaktipriya96@gmail.com wrote:

alloc_workqueue replaces deprecated create_workqueue().

create_workqueue has been replaced with alloc_workqueue with max_active as 0 since there is no need for throttling the number of active work items.

WQ_MEM_RECLAIM has not been set to because kfd_process_wq will not be used in memory reclaim path.

kfd_process_wq is used for delay destruction. A work item embedded in kfd_process gets queued to kfd_process_wq and when it executes it destroys and frees the containing kfd_process and thus itself.

This requires a dedicated workqueue because a work item once queued, may get freed at any point of time and any external entity cannot flush the work item. So, in order to wait for such a work item, it needs to be put on a dedicated workqueue.

kfd_module_exit() calls kfd_process_destroy_wq which ensures that all pending work items are finished before the module is removed.

flush_workqueue is unnecessary since destroy_workqueue() itself calls drain_workqueue() which flushes repeatedly till the workqueue becomes empty.

Hence flush_workqueue has been removed.

Signed-off-by: Bhaktipriya Shridhar bhaktipriya96@gmail.com

Changes in v2: - added explanation for setting concurrency value to WQ_DFL_ACTIVE - added explanation for dropping WQ_MEM_RECLAIM

drivers/gpu/drm/amd/amdkfd/kfd_process.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c index ac00579..b21d3fc8 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c @@ -63,13 +63,12 @@ static struct kfd_process *create_process(const struct task_struct *thread); void kfd_process_create_wq(void) { if (!kfd_process_wq)

•           kfd_process_wq = create_workqueue("kfd_process_wq");
  

•           kfd_process_wq = alloc_workqueue("kfd_process_wq",0,0);
  

You are missing a space between the arguments. Seem you forgot to run checkpatch.pl ;)

Send a new patch and I'll add it to amdkfd's tree.

Thanks,

Oded

}

void kfd_process_destroy_wq(void) { if (kfd_process_wq) {

•           flush_workqueue(kfd_process_wq);
            destroy_workqueue(kfd_process_wq);
            kfd_process_wq = NULL;
    }
  

-- 2.1.4