diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2011-09-30 11:57:58 +0200 |
|---|---|---|
| committer | Clark Williams <williams@redhat.com> | 2012-03-01 09:28:53 -0600 |
| commit | 25ee004d77b1366b03ef54576bde10a2f883d1ac (patch) | |
| tree | 57be7f50705174a3898a40e2d3a088b58b843be9 /include | |
| parent | bec8cc0486d35315f9bb26b39175178e45595d4f (diff) | |
workqueue: Fix cpuhotplug trainwreck
The current workqueue code does crazy stuff on cpu unplug, it relies on
forced affine breakage, thereby violating per-cpu expectations. Worse,
it tries to re-attach to a cpu if the thing comes up again before all
previously queued works are finished. This breaks (admittedly bonkers)
cpu-hotplug use that relies on a down-up cycle to push all usage away.
Introduce a new WQ_NON_AFFINE flag that indicates a per-cpu workqueue
will not respect cpu affinity and use this to migrate all its pending
works to whatever cpu is doing cpu-down.
This also adds a warning for queue_on_cpu() users which warns when its
used on WQ_NON_AFFINE workqueues for the API implies you care about
what cpu things are ran on when such workqueues cannot guarantee this.
For the rest, simply flush all per-cpu works and don't mess about.
This also means that currently all workqueues that are manually
flushing things on cpu-down in order to provide the per-cpu guarantee
no longer need to do so.
In short, we tell the WQ what we want it to do, provide validation for
this and loose ~250 lines of code.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/cpu.h | 6 | ||||
| -rw-r--r-- | include/linux/workqueue.h | 5 |
2 files changed, 7 insertions, 4 deletions
diff --git a/include/linux/cpu.h b/include/linux/cpu.h index c46ec3ecd661..72e90bbf625a 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -66,8 +66,10 @@ enum { /* migration should happen before other stuff but after perf */ CPU_PRI_PERF = 20, CPU_PRI_MIGRATION = 10, - /* prepare workqueues for other notifiers */ - CPU_PRI_WORKQUEUE = 5, + + CPU_PRI_WORKQUEUE_ACTIVE = 5, /* prepare workqueues for others */ + CPU_PRI_NORMAL = 0, + CPU_PRI_WORKQUEUE_INACTIVE = -5, /* flush workqueues after others */ }; #define CPU_ONLINE 0x0002 /* CPU (unsigned)v is up */ diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 0d556deb497b..d68ead81b52b 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -254,9 +254,10 @@ enum { WQ_MEM_RECLAIM = 1 << 3, /* may be used for memory reclaim */ WQ_HIGHPRI = 1 << 4, /* high priority */ WQ_CPU_INTENSIVE = 1 << 5, /* cpu instensive workqueue */ + WQ_NON_AFFINE = 1 << 6, /* free to move works around cpus */ - WQ_DRAINING = 1 << 6, /* internal: workqueue is draining */ - WQ_RESCUER = 1 << 7, /* internal: workqueue has rescuer */ + WQ_DRAINING = 1 << 7, /* internal: workqueue is draining */ + WQ_RESCUER = 1 << 8, /* internal: workqueue has rescuer */ WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */ WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */ |