The patch titled
flush_cpu_workqueue: don't flush an empty ->worklist
has been added to the -mm tree. Its filename is
flush_cpu_workqueue-dont-flush-an-empty-worklist.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: flush_cpu_workqueue: don't flush an empty ->worklist
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Now when we have ->current_work we can avoid adding a barrier and waiting
for its completition when cwq's queue is empty.
Note: this change is also useful if we change flush_workqueue() to also
check the dead CPUs.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Srivatsa Vaddagiri <vatsa@xxxxxxxxxx>
Cc: Gautham Shenoy <ego@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/workqueue.c | 25 +++++++++++++++++--------
1 files changed, 17 insertions(+), 8 deletions(-)
diff -puN kernel/workqueue.c~flush_cpu_workqueue-dont-flush-an-empty-worklist kernel/workqueue.c
--- a/kernel/workqueue.c~flush_cpu_workqueue-dont-flush-an-empty-worklist
+++ a/kernel/workqueue.c
@@ -404,12 +404,15 @@ static void wq_barrier_func(struct work_
complete(&barr->done);
}
-static inline void init_wq_barrier(struct wq_barrier *barr)
+static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
+ struct wq_barrier *barr, int tail)
{
INIT_WORK(&barr->work, wq_barrier_func);
__set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work));
init_completion(&barr->done);
+
+ insert_work(cwq, &barr->work, tail);
}
static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
@@ -428,13 +431,20 @@ static void flush_cpu_workqueue(struct c
preempt_disable();
} else {
struct wq_barrier barr;
+ int active = 0;
- init_wq_barrier(&barr);
- __queue_work(cwq, &barr.work);
+ spin_lock_irq(&cwq->lock);
+ if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) {
+ insert_wq_barrier(cwq, &barr, 1);
+ active = 1;
+ }
+ spin_unlock_irq(&cwq->lock);
- preempt_enable(); /* Can no longer touch *cwq */
- wait_for_completion(&barr.done);
- preempt_disable();
+ if (active) {
+ preempt_enable();
+ wait_for_completion(&barr.done);
+ preempt_disable();
+ }
}
}
@@ -475,8 +485,7 @@ static void wait_on_work(struct cpu_work
spin_lock_irq(&cwq->lock);
if (unlikely(cwq->current_work == work)) {
- init_wq_barrier(&barr);
- insert_work(cwq, &barr.work, 0);
+ insert_wq_barrier(cwq, &barr, 0);
running = 1;
}
spin_unlock_irq(&cwq->lock);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
git-block.patch
doc-atomic_add_unless-doesnt-imply-mb-on-failure.patch
vt-refactor-console-sak-processing.patch
procfs-fix-race-between-proc_readdir-and-remove_proc_entry.patch
procfs-fix-race-between-proc_readdir-and-remove_proc_entry-fix.patch
kill_pid_info-kill-acquired_tasklist_lock.patch
clone-flag-clone_parent_tidptr-leaves-invalid-results-in-memory.patch
tty-make-__proc_set_tty-static.patch
tty-clarify-disassociate_ctty.patch
tty-fix-the-locking-for-signal-session-in-disassociate_ctty.patch
signal-use-kill_pgrp-not-kill_pg-in-the-sunos-compatibility-code.patch
signal-rewrite-kill_something_info-so-it-uses-newer-helpers.patch
pid-make-session_of_pgrp-use-struct-pid-instead-of-pid_t.patch
pid-use-struct-pid-for-talking-about-process-groups-in-exitc.patch
pid-replace-is_orphaned_pgrp-with-is_current_pgrp_orphaned.patch
tty-update-the-tty-layer-to-work-with-struct-pid.patch
pid-replace-do-while_each_task_pid-with-do-while_each_pid_task.patch
pid-remove-now-unused-do_each_task_pid-and-while_each_task_pid.patch
pid-remove-the-now-unused-kill_pg-kill_pg_info-and-__kill_pg_info.patch
reimplement-flush_workqueue.patch
implement-flush_work.patch
implement-flush_work-sanity.patch
implement-flush_work_keventd.patch
flush_workqueue-use-preempt_disable-to-hold-off-cpu-hotplug.patch
flush_cpu_workqueue-dont-flush-an-empty-worklist.patch
aio-use-flush_work.patch
kblockd-use-flush_work.patch
relayfs-use-flush_keventd_work.patch
tg3-use-flush_keventd_work.patch
e1000-use-flush_keventd_work.patch
libata-use-flush_work.patch
phy-use-flush_work.patch
fix-flush_workqueue-vs-cpu_dead-race.patch
-
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