diff options
Diffstat (limited to 'Documentation/core-api')
| -rw-r--r-- | Documentation/core-api/workqueue.rst | 30 |
1 files changed, 23 insertions, 7 deletions
diff --git a/Documentation/core-api/workqueue.rst b/Documentation/core-api/workqueue.rst index 56af317508c9..c73a6df6a118 100644 --- a/Documentation/core-api/workqueue.rst +++ b/Documentation/core-api/workqueue.rst @@ -353,9 +353,10 @@ Affinity Scopes An unbound workqueue groups CPUs according to its affinity scope to improve cache locality. For example, if a workqueue is using the default affinity scope of "cache", it will group CPUs according to last level cache -boundaries. A work item queued on the workqueue will be processed by a -worker running on one of the CPUs which share the last level cache with the -issuing CPU. +boundaries. A work item queued on the workqueue will be assigned to a worker +on one of the CPUs which share the last level cache with the issuing CPU. +Once started, the worker may or may not be allowed to move outside the scope +depending on the ``affinity_strict`` setting of the scope. Workqueue currently supports the following five affinity scopes. @@ -391,6 +392,21 @@ directory. ``affinity_scope`` Read to see the current affinity scope. Write to change. +``affinity_strict`` + 0 by default indicating that affinity scopes are not strict. When a work + item starts execution, workqueue makes a best-effort attempt to ensure + that the worker is inside its affinity scope, which is called + repatriation. Once started, the scheduler is free to move the worker + anywhere in the system as it sees fit. This enables benefiting from scope + locality while still being able to utilize other CPUs if necessary and + available. + + If set to 1, all workers of the scope are guaranteed always to be in the + scope. This may be useful when crossing affinity scopes has other + implications, for example, in terms of power consumption or workload + isolation. Strict NUMA scope can also be used to match the workqueue + behavior of older kernels. + Examining Configuration ======================= @@ -475,21 +491,21 @@ Monitoring Use tools/workqueue/wq_monitor.py to monitor workqueue operations: :: $ tools/workqueue/wq_monitor.py events - total infl CPUtime CPUhog CMwake mayday rescued + total infl CPUtime CPUhog CMW/RPR mayday rescued events 18545 0 6.1 0 5 - - events_highpri 8 0 0.0 0 0 - - events_long 3 0 0.0 0 0 - - - events_unbound 38306 0 0.1 - - - - + events_unbound 38306 0 0.1 - 7 - - events_freezable 0 0 0.0 0 0 - - events_power_efficient 29598 0 0.2 0 0 - - events_freezable_power_ 10 0 0.0 0 0 - - sock_diag_events 0 0 0.0 0 0 - - - total infl CPUtime CPUhog CMwake mayday rescued + total infl CPUtime CPUhog CMW/RPR mayday rescued events 18548 0 6.1 0 5 - - events_highpri 8 0 0.0 0 0 - - events_long 3 0 0.0 0 0 - - - events_unbound 38322 0 0.1 - - - - + events_unbound 38322 0 0.1 - 7 - - events_freezable 0 0 0.0 0 0 - - events_power_efficient 29603 0 0.2 0 0 - - events_freezable_power_ 10 0 0.0 0 0 - - |