sched: affine sync wakeups

make sync wakeups affine for cache-cold tasks: if a cache-cold task
is woken up by a sync wakeup then use the opportunity to migrate it
straight away. (the two tasks are 'related' because they communicate)

Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 12 insertions, 6 deletions

diff --git a/fs/pipe.c b/fs/pipe.c
index f1fa2b412f0e..e66ec48e95d8 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -382,7 +382,7 @@ redo:
 
         /* Signal writers asynchronously that there is more room. */
         if (do_wakeup) {
-                wake_up_interruptible(&pipe->wait);
+                wake_up_interruptible_sync(&pipe->wait);
                 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
         }
         if (ret > 0)
@@ -555,7 +555,7 @@ redo2:
 out:
         mutex_unlock(&inode->i_mutex);
         if (do_wakeup) {
-                wake_up_interruptible(&pipe->wait);
+                wake_up_interruptible_sync(&pipe->wait);
                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
         }
         if (ret > 0)
@@ -649,7 +649,7 @@ pipe_release(struct inode *inode, int decr, int decw)
         if (!pipe->readers && !pipe->writers) {
                 free_pipe_info(inode);
         } else {
-                wake_up_interruptible(&pipe->wait);
+                wake_up_interruptible_sync(&pipe->wait);
                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
                 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
         }
diff --git a/kernel/sched.c b/kernel/sched.c
index 5a91fe0b5de6..7fd343462597 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1521,6 +1521,12 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
                         unsigned long tl = this_load;
                         unsigned long tl_per_task;
 
+                        /*
+                         * Attract cache-cold tasks on sync wakeups:
+                         */
+                        if (sync && !task_hot(p, rq->clock, this_sd))
+                                goto out_set_cpu;
+
                         schedstat_inc(p, se.nr_wakeups_affine_attempts);
                         tl_per_task = cpu_avg_load_per_task(this_cpu);
 
@@ -1598,7 +1604,7 @@ out_activate:
          * the waker guarantees that the freshly woken up task is going
          * to be considered on this CPU.)
          */
-        if (!sync || cpu != this_cpu)
+        if (!sync || rq->curr == rq->idle)
                 check_preempt_curr(rq, p);
         success = 1;
 
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 2b57eaf66abc..6996cba5aa96 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -334,7 +334,7 @@ static void unix_write_space(struct sock *sk)
         read_lock(&sk->sk_callback_lock);
         if (unix_writable(sk)) {
                 if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
-                        wake_up_interruptible(sk->sk_sleep);
+                        wake_up_interruptible_sync(sk->sk_sleep);
                 sk_wake_async(sk, 2, POLL_OUT);
         }
         read_unlock(&sk->sk_callback_lock);
@@ -1639,7 +1639,7 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
         if (!skb)
                 goto out_unlock;
 
-        wake_up_interruptible(&u->peer_wait);
+        wake_up_interruptible_sync(&u->peer_wait);
 
         if (msg->msg_name)
                 unix_copy_addr(msg, skb->sk);