diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 732c5c7e3fa548e97768aeaddabece851229d892..98ffce100a39150dea7b34a283d81f4cdd52e964 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -7014,10 +7014,10 @@
information, see the Affinity Scopes section in
Documentation/core-api/workqueue.rst.
- This can be updated after boot through the matching
- file under /sys/module/workqueue/parameters.
- However, the changed default will only apply to
- unbound workqueues created afterwards.
+ This can be changed after boot by writing to the
+ matching /sys/module/workqueue/parameters file. All
+ workqueues with the "default" affinity scope will be
+ updated accordignly.
workqueue.debug_force_rr_cpu
Workqueue used to implicitly guarantee that work
diff --git a/Documentation/core-api/workqueue.rst b/Documentation/core-api/workqueue.rst
index 4a8e764f41aeaed097a133bd4b436ab2b2e7ee71..5d7b01aed1fe630e7a1b508ae40f3e02d8c687a4 100644
--- a/Documentation/core-api/workqueue.rst
+++ b/Documentation/core-api/workqueue.rst
@@ -358,7 +358,11 @@ 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.
+Workqueue currently supports the following affinity scopes.
+
+``default``
+ Use the scope in module parameter ``workqueue.default_affinity_scope``
+ which is always set to one of the scopes below.
``cpu``
CPUs are not grouped. A work item issued on one CPU is processed by a
@@ -392,6 +396,9 @@ directory.
``affinity_scope``
Read to see the current affinity scope. Write to change.
+ When default is the current scope, reading this file will also show the
+ current effective scope in parentheses, for example, ``default (cache)``.
+
``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
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 0c1cad38f9db61dac9c3555c48160c23becdd04a..1c1d06804d45099f8a3e59ac615e11f65f822370 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -126,6 +126,7 @@ struct rcu_work {
};
enum wq_affn_scope {
+ WQ_AFFN_DFL, /* use system default */
WQ_AFFN_CPU, /* one pod per CPU */
WQ_AFFN_SMT, /* one pod poer SMT */
WQ_AFFN_CACHE, /* one pod per LLC */
@@ -133,8 +134,6 @@ enum wq_affn_scope {
WQ_AFFN_SYSTEM, /* one pod across the whole system */
WQ_AFFN_NR_TYPES,
-
- WQ_AFFN_DFL = WQ_AFFN_CACHE,
};
/**
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 6f6f4f37ceb324eddf9cbf8ad4a7f38dd61ea81b..789e11e72a4a4485653a7cc45f3c3817f9b55506 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -339,9 +339,10 @@ struct wq_pod_type {
};
static struct wq_pod_type wq_pod_types[WQ_AFFN_NR_TYPES];
-static enum wq_affn_scope wq_affn_dfl = WQ_AFFN_DFL;
+static enum wq_affn_scope wq_affn_dfl = WQ_AFFN_CACHE;
static const char *wq_affn_names[WQ_AFFN_NR_TYPES] = {
+ [WQ_AFFN_DFL] = "default",
[WQ_AFFN_CPU] = "cpu",
[WQ_AFFN_SMT] = "smt",
[WQ_AFFN_CACHE] = "cache",
@@ -3734,7 +3735,7 @@ struct workqueue_attrs *alloc_workqueue_attrs(void)
goto fail;
cpumask_copy(attrs->cpumask, cpu_possible_mask);
- attrs->affn_scope = wq_affn_dfl;
+ attrs->affn_scope = WQ_AFFN_DFL;
return attrs;
fail:
free_workqueue_attrs(attrs);
@@ -3815,7 +3816,18 @@ static void wqattrs_actualize_cpumask(struct workqueue_attrs *attrs,
static const struct wq_pod_type *
wqattrs_pod_type(const struct workqueue_attrs *attrs)
{
- struct wq_pod_type *pt = &wq_pod_types[attrs->affn_scope];
+ enum wq_affn_scope scope;
+ struct wq_pod_type *pt;
+
+ /* to synchronize access to wq_affn_dfl */
+ lockdep_assert_held(&wq_pool_mutex);
+
+ if (attrs->affn_scope == WQ_AFFN_DFL)
+ scope = wq_affn_dfl;
+ else
+ scope = attrs->affn_scope;
+
+ pt = &wq_pod_types[scope];
if (!WARN_ON_ONCE(attrs->affn_scope == WQ_AFFN_NR_TYPES) &&
likely(pt->nr_pods))
@@ -5847,13 +5859,29 @@ static int parse_affn_scope(const char *val)
static int wq_affn_dfl_set(const char *val, const struct kernel_param *kp)
{
- int affn;
+ struct workqueue_struct *wq;
+ int affn, cpu;
affn = parse_affn_scope(val);
if (affn < 0)
return affn;
+ if (affn == WQ_AFFN_DFL)
+ return -EINVAL;
+
+ cpus_read_lock();
+ mutex_lock(&wq_pool_mutex);
wq_affn_dfl = affn;
+
+ list_for_each_entry(wq, &workqueues, list) {
+ for_each_online_cpu(cpu) {
+ wq_update_pod(wq, cpu, cpu, true);
+ }
+ }
+
+ mutex_unlock(&wq_pool_mutex);
+ cpus_read_unlock();
+
return 0;
}
@@ -6033,8 +6061,13 @@ static ssize_t wq_affn_scope_show(struct device *dev,
int written;
mutex_lock(&wq->mutex);
- written = scnprintf(buf, PAGE_SIZE, "%s\n",
- wq_affn_names[wq->unbound_attrs->affn_scope]);
+ if (wq->unbound_attrs->affn_scope == WQ_AFFN_DFL)
+ written = scnprintf(buf, PAGE_SIZE, "%s (%s)\n",
+ wq_affn_names[WQ_AFFN_DFL],
+ wq_affn_names[wq_affn_dfl]);
+ else
+ written = scnprintf(buf, PAGE_SIZE, "%s\n",
+ wq_affn_names[wq->unbound_attrs->affn_scope]);
mutex_unlock(&wq->mutex);
return written;