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authorTejun Heo <tj@kernel.org>2015-12-08 19:28:04 +0300
committerTejun Heo <tj@kernel.org>2015-12-08 19:29:47 +0300
commit82607adcf9cdf40fb7b5331269780c8f70ec6e35 (patch)
tree22c7849ef8e873007dd56a63b109937046d897db /Documentation/kernel-parameters.txt
parent03e0d4610bf4d4a93bfa16b2474ed4fd5243aa71 (diff)
downloadlinux-82607adcf9cdf40fb7b5331269780c8f70ec6e35.tar.xz
workqueue: implement lockup detector
Workqueue stalls can happen from a variety of usage bugs such as missing WQ_MEM_RECLAIM flag or concurrency managed work item indefinitely staying RUNNING. These stalls can be extremely difficult to hunt down because the usual warning mechanisms can't detect workqueue stalls and the internal state is pretty opaque. To alleviate the situation, this patch implements workqueue lockup detector. It periodically monitors all worker_pools periodically and, if any pool failed to make forward progress longer than the threshold duration, triggers warning and dumps workqueue state as follows. BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 31s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=17/256 pending: monkey_wrench_fn, e1000_watchdog, cache_reap, vmstat_shepherd, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, cgroup_release_agent workqueue events_power_efficient: flags=0x80 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256 pending: check_lifetime, neigh_periodic_work workqueue cgroup_pidlist_destroy: flags=0x0 pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1 pending: cgroup_pidlist_destroy_work_fn ... The detection mechanism is controller through kernel parameter workqueue.watchdog_thresh and can be updated at runtime through the sysfs module parameter file. v2: Decoupled from softlockup control knobs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Don Zickus <dzickus@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt9
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 742f69d18fc8..fb6c93f36e3b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -4114,6 +4114,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
or other driver-specific files in the
Documentation/watchdog/ directory.
+ workqueue.watchdog_thresh=
+ If CONFIG_WQ_WATCHDOG is configured, workqueue can
+ warn stall conditions and dump internal state to
+ help debugging. 0 disables workqueue stall
+ detection; otherwise, it's the stall threshold
+ duration in seconds. The default value is 30 and
+ it can be updated at runtime by writing to the
+ corresponding sysfs file.
+
workqueue.disable_numa
By default, all work items queued to unbound
workqueues are affine to the NUMA nodes they're