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Subject[PATCH 3/4 V5] workqueue: Create low-level unbound workqueues cpumask
Date
From: Frederic Weisbecker <fweisbec@gmail.com>

Create a cpumask that limit the affinity of all unbound workqueues.
This cpumask is controlled though a file at the root of the workqueue
sysfs directory.

It works on a lower-level than the per WQ_SYSFS workqueues cpumask files
such that the effective cpumask applied for a given unbound workqueue is
the intersection of /sys/devices/virtual/workqueue/$WORKQUEUE/cpumask and
the new /sys/devices/virtual/workqueue/cpumask_unbounds file.

This patch implements the basic infrastructure and the read interface.
cpumask_unbounds is initially set to cpu_possible_mask.

Cc: Christoph Lameter <cl@linux.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Mike Galbraith <bitbucket@online.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
kernel/workqueue.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index b150828..d1197f0 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -299,6 +299,8 @@ static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
static LIST_HEAD(workqueues); /* PR: list of all workqueues */
static bool workqueue_freezing; /* PL: have wqs started freezing? */

+static cpumask_var_t wq_unbound_cpumask;
+
/* the per-cpu worker pools */
static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
cpu_worker_pools);
@@ -3532,7 +3534,7 @@ wq_unbound_install_ctx_prepare(struct workqueue_struct *wq,

/* make a copy of @attrs and sanitize it */
copy_workqueue_attrs(new_attrs, attrs);
- cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
+ cpumask_and(new_attrs->cpumask, new_attrs->cpumask, wq_unbound_cpumask);

/*
* We may create multiple pwqs with differing cpumasks. Make a
@@ -3963,9 +3965,29 @@ static struct bus_type wq_subsys = {
.dev_groups = wq_sysfs_groups,
};

+static ssize_t unbounds_cpumask_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ int written;
+
+ written = scnprintf(buf, PAGE_SIZE, "%*pb\n",
+ cpumask_pr_args(wq_unbound_cpumask));
+
+ return written;
+}
+
+static struct device_attribute wq_sysfs_cpumask_attr =
+ __ATTR(cpumask, 0444, unbounds_cpumask_show, NULL);
+
static int __init wq_sysfs_init(void)
{
- return subsys_virtual_register(&wq_subsys, NULL);
+ int err;
+
+ err = subsys_virtual_register(&wq_subsys, NULL);
+ if (err)
+ return err;
+
+ return device_create_file(wq_subsys.dev_root, &wq_sysfs_cpumask_attr);
}
core_initcall(wq_sysfs_init);

@@ -5098,6 +5120,9 @@ static int __init init_workqueues(void)

WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));

+ BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL));
+ cpumask_copy(wq_unbound_cpumask, cpu_possible_mask);
+
pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);

cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
--
2.1.0


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