[POWERPC] spusched: Disable tick when not needed

Only enable the scheduler tick if we have any context waiting to be
scheduled.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index bb16c22360d51087150048fd70cf0f217dfb2979..2fb0e63344ccd63c523bfe53f01796a6ac9da43b 100644 (file)
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -294,9 +294,10 @@ static void __spu_add_to_rq(struct spu_context *ctx)
 {
        int prio = ctx->prio;
 
-       spu_prio->nr_waiting++;
        list_add_tail(&ctx->rq, &spu_prio->runq[prio]);
        set_bit(prio, spu_prio->bitmap);
+       if (!spu_prio->nr_waiting++)
+               __mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
 }
 
 static void __spu_del_from_rq(struct spu_context *ctx)
@@ -304,11 +305,13 @@ static void __spu_del_from_rq(struct spu_context *ctx)
        int prio = ctx->prio;
 
        if (!list_empty(&ctx->rq)) {
+               if (!--spu_prio->nr_waiting)
+                       del_timer(&spusched_timer);
                list_del_init(&ctx->rq);
-               spu_prio->nr_waiting--;
+
+               if (list_empty(&spu_prio->runq[prio]))
+                       clear_bit(prio, spu_prio->bitmap);
        }
-       if (list_empty(&spu_prio->runq[prio]))
-               clear_bit(prio, spu_prio->bitmap);
 }
 
 static void spu_prio_wait(struct spu_context *ctx)
@@ -654,9 +657,6 @@ static int spusched_thread(void *unused)
        struct spu *spu, *next;
        int node;
 
-       setup_timer(&spusched_timer, spusched_wake, 0);
-       __mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
-
        while (!kthread_should_stop()) {
                set_current_state(TASK_INTERRUPTIBLE);
                schedule();
@@ -670,7 +670,6 @@ static int spusched_thread(void *unused)
                }
        }
 
-       del_timer_sync(&spusched_timer);
        return 0;
 }
 
@@ -732,6 +731,8 @@ int __init spu_sched_init(void)
        }
        spin_lock_init(&spu_prio->runq_lock);
 
+       setup_timer(&spusched_timer, spusched_wake, 0);
+
        spusched_task = kthread_run(spusched_thread, NULL, "spusched");
        if (IS_ERR(spusched_task)) {
                err = PTR_ERR(spusched_task);
@@ -762,6 +763,7 @@ void __exit spu_sched_exit(void)
 
        remove_proc_entry("spu_loadavg", NULL);
 
+       del_timer_sync(&spusched_timer);
        kthread_stop(spusched_task);
 
        for (node = 0; node < MAX_NUMNODES; node++) {