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| author |   Prateek Sood <prsood@codeaurora.org> | 2020-01-24 20:37:29 +0530 |
|---|---|---|
| committer |   Tejun Heo <tj@kernel.org> | 2020-02-12 17:13:47 -0500 |
| commit | a49e4629b5edf1db856de05fbf1aae05502ef1af (patch) | |
| tree | 11eed372fa154e9be6144e790581102f0ec5f4a2 /kernel/cgroup | |
| parent | cgroup.c: Use built-in RCU list checking (diff) | |
| download | linux-dev-a49e4629b5edf1db856de05fbf1aae05502ef1af.tar.xz linux-dev-a49e4629b5edf1db856de05fbf1aae05502ef1af.zip | |
cpuset: Make cpuset hotplug synchronous
Convert cpuset_hotplug_workfn() into synchronous call for cpu hotplug
path. For memory hotplug path it still gets queued as a work item.
Since cpuset_hotplug_workfn() can be made synchronous for cpu hotplug
path, it is not required to wait for cpuset hotplug while thawing
processes.
Signed-off-by: Prateek Sood <prsood@codeaurora.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup')
| -rw-r--r-- | kernel/cgroup/cpuset.c | 31 |
1 files changed, 19 insertions, 12 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 58f5073acff7..cafd4d2ff882 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -3101,7 +3101,7 @@ update_tasks: } /** - * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset + * cpuset_hotplug - handle CPU/memory hotunplug for a cpuset * * This function is called after either CPU or memory configuration has * changed and updates cpuset accordingly. The top_cpuset is always @@ -3116,7 +3116,7 @@ update_tasks: * Note that CPU offlining during suspend is ignored. We don't modify * cpusets across suspend/resume cycles at all. */ -static void cpuset_hotplug_workfn(struct work_struct *work) +static void cpuset_hotplug(bool use_cpu_hp_lock) { static cpumask_t new_cpus; static nodemask_t new_mems; @@ -3201,25 +3201,32 @@ static void cpuset_hotplug_workfn(struct work_struct *work) /* rebuild sched domains if cpus_allowed has changed */ if (cpus_updated || force_rebuild) { force_rebuild = false; - rebuild_sched_domains(); + if (use_cpu_hp_lock) + rebuild_sched_domains(); + else { + /* Acquiring cpu_hotplug_lock is not required. + * When cpuset_hotplug() is called in hotplug path, + * cpu_hotplug_lock is held by the hotplug context + * which is waiting for cpuhp_thread_fun to indicate + * completion of callback. + */ + percpu_down_write(&cpuset_rwsem); + rebuild_sched_domains_locked(); + percpu_up_write(&cpuset_rwsem); + } } free_cpumasks(NULL, ptmp); } -void cpuset_update_active_cpus(void) +static void cpuset_hotplug_workfn(struct work_struct *work) { - /* - * We're inside cpu hotplug critical region which usually nests - * inside cgroup synchronization. Bounce actual hotplug processing - * to a work item to avoid reverse locking order. - */ - schedule_work(&cpuset_hotplug_work); + cpuset_hotplug(true); } -void cpuset_wait_for_hotplug(void) +void cpuset_update_active_cpus(void) { - flush_work(&cpuset_hotplug_work); + cpuset_hotplug(false); } /* |