On Fri, Jan 09, 2026 at 04:57:17PM +0100, Marco Crivellari wrote:
> This patch continues the effort to refactor workqueue APIs, which has begun
> with the changes introducing new workqueues and a new alloc_workqueue flag:
>
> commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
> commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
>
> The point of the refactoring is to eventually alter the default behavior of
> workqueues to become unbound by default so that their workload placement is
> optimized by the scheduler.
>
> Before that to happen, workqueue users must be converted to the better named
> new workqueues with no intended behaviour changes:
>
> system_wq -> system_percpu_wq
> system_unbound_wq -> system_dfl_wq
>
> This way the old obsolete workqueues (system_wq, system_unbound_wq) can be
> removed in the future.
>
> After a carefully evaluation, because this is the fence signaling path, we
> changed the code in order to use one of the Xe's workqueue.
>
> So, a new workqueue named 'fence_signal_wq' has been added to
> 'struct xe_tlb_inval' and has been initialized with 'gt->ordered_wq'
> changing the system_wq uses with tlb_inval->fence_signal_wq.
>
> Link: https://lore.kernel.org/all/[email protected]/
> Suggested-by: Tejun Heo <[email protected]>
> Signed-off-by: Marco Crivellari <[email protected]>
> ---
> Changes in v2:
> - added 'fence_signal_wq', initialized with 'gt->ordered_wq' in order to use
> it in the fence signaling path, instead of system_wq.
>
> - rebased on v6.19-rc4
>
>
> drivers/gpu/drm/xe/xe_tlb_inval.c | 10 +++++++---
> drivers/gpu/drm/xe/xe_tlb_inval_types.h | 2 ++
> 2 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_tlb_inval.c
> b/drivers/gpu/drm/xe/xe_tlb_inval.c
> index 918a59e686ea..2e98f407c59d 100644
> --- a/drivers/gpu/drm/xe/xe_tlb_inval.c
> +++ b/drivers/gpu/drm/xe/xe_tlb_inval.c
> @@ -94,7 +94,7 @@ static void xe_tlb_inval_fence_timeout(struct work_struct
> *work)
> xe_tlb_inval_fence_signal(fence);
> }
> if (!list_empty(&tlb_inval->pending_fences))
> - queue_delayed_work(system_wq, &tlb_inval->fence_tdr,
> + queue_delayed_work(tlb_inval->fence_signal_wq,
> &tlb_inval->fence_tdr,
> timeout_delay);
> spin_unlock_irq(&tlb_inval->pending_lock);
> }
> @@ -146,6 +146,10 @@ int xe_gt_tlb_inval_init_early(struct xe_gt *gt)
> if (IS_ERR(tlb_inval->job_wq))
> return PTR_ERR(tlb_inval->job_wq);
>
> + tlb_inval->fence_signal_wq = gt->ordered_wq;
> + if (IS_ERR(tlb_inval->fence_signal_wq))
> + return PTR_ERR(tlb_inval->fence_signal_wq);
> +
> /* XXX: Blindly setting up backend to GuC */
> xe_guc_tlb_inval_init_early(>->uc.guc, tlb_inval);
>
> @@ -226,7 +230,7 @@ static void xe_tlb_inval_fence_prep(struct
> xe_tlb_inval_fence *fence)
> list_add_tail(&fence->link, &tlb_inval->pending_fences);
>
> if (list_is_singular(&tlb_inval->pending_fences))
> - queue_delayed_work(system_wq, &tlb_inval->fence_tdr,
> + queue_delayed_work(tlb_inval->fence_signal_wq,
> &tlb_inval->fence_tdr,
> tlb_inval->ops->timeout_delay(tlb_inval));
> spin_unlock_irq(&tlb_inval->pending_lock);
>
> @@ -378,7 +382,7 @@ void xe_tlb_inval_done_handler(struct xe_tlb_inval
> *tlb_inval, int seqno)
> }
>
> if (!list_empty(&tlb_inval->pending_fences))
> - mod_delayed_work(system_wq,
> + mod_delayed_work(tlb_inval->fence_signal_wq,
> &tlb_inval->fence_tdr,
> tlb_inval->ops->timeout_delay(tlb_inval));
> else
> diff --git a/drivers/gpu/drm/xe/xe_tlb_inval_types.h
> b/drivers/gpu/drm/xe/xe_tlb_inval_types.h
> index 8f8b060e9005..1a3e239ea3a7 100644
> --- a/drivers/gpu/drm/xe/xe_tlb_inval_types.h
> +++ b/drivers/gpu/drm/xe/xe_tlb_inval_types.h
> @@ -106,6 +106,8 @@ struct xe_tlb_inval {
> struct workqueue_struct *job_wq;
> /** @tlb_inval.lock: protects TLB invalidation fences */
> spinlock_t lock;
> + /** @fence_signal_wq: schedule fence signaling path jobs */
> + struct workqueue_struct *fence_signal_wq;
I hate to be nitpicky but this name / kernel doc isn't great.
How about:
/** @timeout_wq: schedules TLB invalidation fence timeouts */
struct workqueue_struct *timeout_wq;
Functionality everything in this patch looks correct.
Matt
> };
>
> /**
> --
> 2.52.0
>
