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Commit 71e20f18 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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: default avatarIngo Molnar <mingo@elte.hu>
parent d172fcd3

fs/pipe.c

+3 −3
Original line number Diff line number Diff line
@@ -382,7 +382,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov, 


	/* 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 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov, 
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);

	}

kernel/sched.c

+7 −1
Original line number Diff line number Diff line
@@ -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 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) 
	 * 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;

net/unix/af_unix.c

+2 −2
Original line number Diff line number Diff line
@@ -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);