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[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: Jens Axboe <axboe@suse.de>
This commit is contained in:
Jens Axboe 2006-04-11 13:53:56 +02:00
parent 923f4f2394
commit 6f767b0425
1 changed files with 13 additions and 20 deletions
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33
fs/splice.c
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@ -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;
@ -174,8 +171,9 @@ 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;
do_wakeup = 1;
pipe->nrbufs++;
if (pipe->inode)
do_wakeup = 1;
ret += this_len;
len -= 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;
@ -606,10 +601,10 @@ 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;
do_wakeup = 1;
pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
pipe->nrbufs--;
if (pipe->inode)
do_wakeup = 1;
}
sd.pos += sd.len;
@ -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;
}