Re: [PATCH 4/5] Btrfs: batch the extent state operation in the end io handle of the read page
On Thu, Jul 11, 2013 at 01:25:39PM +0800, Miao Xie wrote:
> It is unnecessary to unlock the extent by the page size, we can do it
> in batches, it makes the random read be faster by ~6%.
>
> Signed-off-by: Miao Xie
> ---
> fs/btrfs/extent_io.c | 70
> ++--
> 1 file changed, 40 insertions(+), 30 deletions(-)
>
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index 9f4dedf..8f95418 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -762,15 +762,6 @@ static void cache_state(struct extent_state *state,
> }
> }
>
> -static void uncache_state(struct extent_state **cached_ptr)
> -{
> - if (cached_ptr && (*cached_ptr)) {
> - struct extent_state *state = *cached_ptr;
> - *cached_ptr = NULL;
> - free_extent_state(state);
> - }
> -}
> -
> /*
> * set some bits on a range in the tree. This may require allocations or
> * sleeping, so the gfp mask is used to indicate what is allowed.
> @@ -2395,6 +2386,18 @@ static void end_bio_extent_writepage(struct bio *bio,
> int err)
> bio_put(bio);
> }
>
> +static void
> +endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64
> len,
> + int uptodate)
> +{
> + struct extent_state *cached = NULL;
> + u64 end = start + len - 1;
> +
> + if (uptodate && tree->track_uptodate)
> + set_extent_uptodate(tree, start, end, &cached, GFP_ATOMIC);
> + unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
> +}
> +
> /*
> * after a readpage IO is done, we need to:
> * clear the uptodate bits on error
> @@ -2417,6 +2420,8 @@ static void end_bio_extent_readpage(struct bio *bio,
> int err)
> u64 start;
> u64 end;
> u64 len;
> + u64 extent_start = 0;
> + u64 extent_len = 0;
> int mirror;
> int ret;
>
> @@ -2425,8 +2430,6 @@ static void end_bio_extent_readpage(struct bio *bio,
> int err)
>
> do {
> struct page *page = bvec->bv_page;
> - struct extent_state *cached = NULL;
> - struct extent_state *state;
> struct inode *inode = page->mapping->host;
>
> pr_debug("end_bio_extent_readpage: bi_sector=%llu, err=%d, "
> @@ -2452,17 +2455,6 @@ static void end_bio_extent_readpage(struct bio *bio,
> int err)
> if (++bvec <= bvec_end)
> prefetchw(&bvec->bv_page->flags);
>
> - spin_lock(&tree->lock);
> - state = find_first_extent_bit_state(tree, start, EXTENT_LOCKED);
> - if (likely(state && state->start == start)) {
> - /*
> - * take a reference on the state, unlock will drop
> - * the ref
> - */
> - cache_state(state, &cached);
> - }
> - spin_unlock(&tree->lock);
> -
> mirror = io_bio->mirror_num;
> if (likely(uptodate && tree->ops &&
> tree->ops->readpage_end_io_hook)) {
> @@ -2501,18 +2493,11 @@ static void end_bio_extent_readpage(struct bio *bio,
> int err)
> test_bit(BIO_UPTODATE, &bio->bi_flags);
> if (err)
> uptodate = 0;
> - uncache_state(&cached);
> continue;
> }
> }
> readpage_ok:
> - if (uptodate && tree->track_uptodate) {
> - set_extent_uptodate(tree, start, end, &cached,
> - GFP_ATOMIC);
> - }
> - unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
> -
> - if (uptodate) {
> + if (likely(uptodate)) {
> loff_t i_size = i_size_read(inode);
> pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
> unsigned offset;
> @@ -2528,8 +2513,33 @@ readpage_ok:
> }
> unlock_page(page);
> offset += len;
> +
> + if (unlikely(!uptodate)) {
> + if (extent_len) {
> + endio_readpage_release_extent(tree,
> + extent_start,
> + extent_len, 1);
> + extent_start = 0;
> + extent_len = 0;
> + }
> + endio_readpage_release_extent(tree, start,
> + end - start + 1, 0);
> + } else if (!extent_len) {
> + extent_start = start;
> + extent_len = end + 1 - start;
> + } else if (extent_start + extent_len == start) {
> +
[PATCH 4/5] Btrfs: batch the extent state operation in the end io handle of the read page
It is unnecessary to unlock the extent by the page size, we can do it
in batches, it makes the random read be faster by ~6%.
Signed-off-by: Miao Xie
---
fs/btrfs/extent_io.c | 70 ++--
1 file changed, 40 insertions(+), 30 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 9f4dedf..8f95418 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -762,15 +762,6 @@ static void cache_state(struct extent_state *state,
}
}
-static void uncache_state(struct extent_state **cached_ptr)
-{
- if (cached_ptr && (*cached_ptr)) {
- struct extent_state *state = *cached_ptr;
- *cached_ptr = NULL;
- free_extent_state(state);
- }
-}
-
/*
* set some bits on a range in the tree. This may require allocations or
* sleeping, so the gfp mask is used to indicate what is allowed.
@@ -2395,6 +2386,18 @@ static void end_bio_extent_writepage(struct bio *bio,
int err)
bio_put(bio);
}
+static void
+endio_readpage_release_extent(struct extent_io_tree *tree, u64 start, u64 len,
+ int uptodate)
+{
+ struct extent_state *cached = NULL;
+ u64 end = start + len - 1;
+
+ if (uptodate && tree->track_uptodate)
+ set_extent_uptodate(tree, start, end, &cached, GFP_ATOMIC);
+ unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
+}
+
/*
* after a readpage IO is done, we need to:
* clear the uptodate bits on error
@@ -2417,6 +2420,8 @@ static void end_bio_extent_readpage(struct bio *bio, int
err)
u64 start;
u64 end;
u64 len;
+ u64 extent_start = 0;
+ u64 extent_len = 0;
int mirror;
int ret;
@@ -2425,8 +2430,6 @@ static void end_bio_extent_readpage(struct bio *bio, int
err)
do {
struct page *page = bvec->bv_page;
- struct extent_state *cached = NULL;
- struct extent_state *state;
struct inode *inode = page->mapping->host;
pr_debug("end_bio_extent_readpage: bi_sector=%llu, err=%d, "
@@ -2452,17 +2455,6 @@ static void end_bio_extent_readpage(struct bio *bio, int
err)
if (++bvec <= bvec_end)
prefetchw(&bvec->bv_page->flags);
- spin_lock(&tree->lock);
- state = find_first_extent_bit_state(tree, start, EXTENT_LOCKED);
- if (likely(state && state->start == start)) {
- /*
-* take a reference on the state, unlock will drop
-* the ref
-*/
- cache_state(state, &cached);
- }
- spin_unlock(&tree->lock);
-
mirror = io_bio->mirror_num;
if (likely(uptodate && tree->ops &&
tree->ops->readpage_end_io_hook)) {
@@ -2501,18 +2493,11 @@ static void end_bio_extent_readpage(struct bio *bio,
int err)
test_bit(BIO_UPTODATE, &bio->bi_flags);
if (err)
uptodate = 0;
- uncache_state(&cached);
continue;
}
}
readpage_ok:
- if (uptodate && tree->track_uptodate) {
- set_extent_uptodate(tree, start, end, &cached,
- GFP_ATOMIC);
- }
- unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);
-
- if (uptodate) {
+ if (likely(uptodate)) {
loff_t i_size = i_size_read(inode);
pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
unsigned offset;
@@ -2528,8 +2513,33 @@ readpage_ok:
}
unlock_page(page);
offset += len;
+
+ if (unlikely(!uptodate)) {
+ if (extent_len) {
+ endio_readpage_release_extent(tree,
+ extent_start,
+ extent_len, 1);
+ extent_start = 0;
+ extent_len = 0;
+ }
+ endio_readpage_release_extent(tree, start,
+ end - start + 1, 0);
+ } else if (!extent_len) {
+ extent_start = start;
+ extent_len = end + 1 - start;
+ } else if (extent_start + extent_len == start) {
+ extent_len += end + 1 - start;
+ } else {
+ endio_readpage_release_extent(tree, extent_start,
+
