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Commit 6f767b04 authored by Jens Axboe's avatar Jens Axboe
Browse files

[PATCH] splice: speedups and optimizations 



- Kill the local variables that cache ->nrbufs, they just take up space.

- Only set do_wakeup for a real pipe. This is a big win for direct splicing.

- Kill i_mutex lock around ->f_pos update, regular io paths don't do this
  either.

Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent 923f4f23

fs/splice.c

+13 −20
Original line number Diff line number Diff line
@@ -150,8 +150,6 @@ static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages, 
		mutex_lock(&pipe->inode->i_mutex);



	for (;;) {

		int bufs;



		if (!pipe->readers) {

			send_sig(SIGPIPE, current, 0);

			if (!ret)
@@ -159,9 +157,8 @@ static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages, 
			break;

		}



		bufs = pipe->nrbufs;

		if (bufs < PIPE_BUFFERS) {

			int newbuf = (pipe->curbuf + bufs) & (PIPE_BUFFERS - 1);

		if (pipe->nrbufs < PIPE_BUFFERS) {

			int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);

			struct pipe_buffer *buf = pipe->bufs + newbuf;

			struct page *page = pages[i++];

			unsigned long this_len;
@@ -174,7 +171,8 @@ static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages, 
			buf->offset = offset;

			buf->len = this_len;

			buf->ops = &page_cache_pipe_buf_ops;

			pipe->nrbufs = ++bufs;

			pipe->nrbufs++;

			if (pipe->inode)

				do_wakeup = 1;



			ret += this_len;
@@ -184,7 +182,7 @@ static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages, 
				break;

			if (!len)

				break;

			if (bufs < PIPE_BUFFERS)

			if (pipe->nrbufs < PIPE_BUFFERS)

				continue;



			break;
@@ -581,11 +579,8 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out, 
		mutex_lock(&pipe->inode->i_mutex);



	for (;;) {

		int bufs = pipe->nrbufs;



		if (bufs) {

			int curbuf = pipe->curbuf;

			struct pipe_buffer *buf = pipe->bufs + curbuf;

		if (pipe->nrbufs) {

			struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;

			struct pipe_buf_operations *ops = buf->ops;



			sd.len = buf->len;
@@ -606,9 +601,9 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out, 
			if (!buf->len) {

				buf->ops = NULL;

				ops->release(pipe, buf);

				curbuf = (curbuf + 1) & (PIPE_BUFFERS - 1);

				pipe->curbuf = curbuf;

				pipe->nrbufs = --bufs;

				pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);

				pipe->nrbufs--;

				if (pipe->inode)

					do_wakeup = 1;

			}
@@ -618,7 +613,7 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out, 
				break;

		}



		if (bufs)

		if (pipe->nrbufs)

			continue;

		if (!pipe->writers)

			break;
@@ -660,9 +655,7 @@ static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out, 
		kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);

	}



	mutex_lock(&out->f_mapping->host->i_mutex);

	out->f_pos = sd.pos;

	mutex_unlock(&out->f_mapping->host->i_mutex);

	return ret;



}