[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>
diff --git a/fs/splice.c b/fs/splice.c
index e30743c..36bc262 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -150,8 +150,6 @@
mutex_lock(&pipe->inode->i_mutex);
for (;;) {
- int bufs;
-
if (!pipe->readers) {
send_sig(SIGPIPE, current, 0);
if (!ret)
@@ -159,9 +157,8 @@
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 @@
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 @@
break;
if (!len)
break;
- if (bufs < PIPE_BUFFERS)
+ if (pipe->nrbufs < PIPE_BUFFERS)
continue;
break;
@@ -581,11 +579,8 @@
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 @@
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 @@
break;
}
- if (bufs)
+ if (pipe->nrbufs)
continue;
if (!pipe->writers)
break;
@@ -660,9 +655,7 @@
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;
}