Hi Marco, thanks for addressing my comments!
Reviewed-by: Krzysztof Karas <[email protected]> on the whole series. Best Regards, Krzysztof On 2025-11-04 at 11:00:29 +0100, Marco Crivellari wrote: > Hi, > > === Current situation: problems === > > Let's consider a nohz_full system with isolated CPUs: wq_unbound_cpumask is > set to the housekeeping CPUs, for !WQ_UNBOUND the local CPU is selected. > > This leads to different scenarios if a work item is scheduled on an > isolated CPU where "delay" value is 0 or greater then 0: > schedule_delayed_work(, 0); > > This will be handled by __queue_work() that will queue the work item on the > current local (isolated) CPU, while: > > schedule_delayed_work(, 1); > > Will move the timer on an housekeeping CPU, and schedule the work there. > > Currently if a user enqueue a work item using schedule_delayed_work() the > used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use > WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to > schedule_work() that is using system_wq and queue_work(), that makes use > again of WORK_CPU_UNBOUND. > > This lack of consistency cannot be addressed without refactoring the API. > > === Recent changes to the WQ API === > > The following, address the recent changes in the Workqueue API: > > - commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq") > - commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag") > > The old workqueues will be removed in a future release cycle. > > === Introduced Changes by this series === > > 1) [P 1-2] Replace uses of system_wq and system_unbound_wq > > system_wq is a per-CPU workqueue, but his name is not clear. > system_unbound_wq is to be used when locality is not required. > > Because of that, system_wq has been replaced with system_percpu_wq, and > system_unbound_wq has been replaced with system_dfl_wq. > > 2) [P 3] WQ_PERCPU added to alloc_workqueue() > > This change adds a new WQ_PERCPU flag to explicitly request > alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified. > > > Thanks! > > --- > Changes in 3: > - Improved commit logs > > Changes in v2: > - fix typo in patch subject (add instead of added). > > - in every patch is also present the specific commit hash about the > workqueue API change. > > - fixed commit log of P1 (removed "Adding system_dfl_wq..."). > > - P2: subject changed reflecting the effective change. > > - rebased to v6.18-rc4. > > > Marco Crivellari (3): > drm/i915: replace use of system_unbound_wq with system_dfl_wq > drm/i915: replace use of system_wq with system_percpu_wq in the > documentation > drm/i915: add WQ_PERCPU to alloc_workqueue users > > drivers/gpu/drm/i915/display/intel_display_driver.c | 4 ++-- > drivers/gpu/drm/i915/display/intel_display_power.c | 2 +- > drivers/gpu/drm/i915/display/intel_tc.c | 4 ++-- > drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c | 2 +- > drivers/gpu/drm/i915/gt/uc/intel_guc.c | 4 ++-- > drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 4 ++-- > drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 6 +++--- > drivers/gpu/drm/i915/i915_active.c | 2 +- > drivers/gpu/drm/i915/i915_driver.c | 5 +++-- > drivers/gpu/drm/i915/i915_drv.h | 2 +- > drivers/gpu/drm/i915/i915_sw_fence_work.c | 2 +- > drivers/gpu/drm/i915/i915_vma_resource.c | 2 +- > drivers/gpu/drm/i915/pxp/intel_pxp.c | 2 +- > drivers/gpu/drm/i915/pxp/intel_pxp_irq.c | 2 +- > drivers/gpu/drm/i915/selftests/i915_sw_fence.c | 2 +- > drivers/gpu/drm/i915/selftests/mock_gem_device.c | 2 +- > 16 files changed, 24 insertions(+), 23 deletions(-) > > -- > 2.51.1 >
