Btrfs: do not async metadata csumming in certain situations
There are a coule scenarios where farming metadata csumming off to an async
thread doesn't help. The first is if our processor supports crc32c, in
which case the csumming will be fast and so the overhead of the async model
is not worth the cost. The other case is for our tree log. We will be
making that stuff dirty and writing it out and waiting for it immediately.
Even with software crc32c this gives me a ~15% increase in speed with O_SYNC
workloads. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index a2c2157..979fa0d 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -45,6 +45,7 @@
struct bio *bio;
struct extent_io_tree *tree;
get_extent_t *get_extent;
+ unsigned long bio_flags;
/* tells writepage not to lock the state bits for this range
* it still does the unlocking
@@ -3163,12 +3164,16 @@
struct block_device *bdev = fs_info->fs_devices->latest_bdev;
u64 offset = eb->start;
unsigned long i, num_pages;
+ unsigned long bio_flags = 0;
int rw = (epd->sync_io ? WRITE_SYNC : WRITE);
int ret = 0;
clear_bit(EXTENT_BUFFER_IOERR, &eb->bflags);
num_pages = num_extent_pages(eb->start, eb->len);
atomic_set(&eb->io_pages, num_pages);
+ if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID)
+ bio_flags = EXTENT_BIO_TREE_LOG;
+
for (i = 0; i < num_pages; i++) {
struct page *p = extent_buffer_page(eb, i);
@@ -3177,7 +3182,8 @@
ret = submit_extent_page(rw, eb->tree, p, offset >> 9,
PAGE_CACHE_SIZE, 0, bdev, &epd->bio,
-1, end_bio_extent_buffer_writepage,
- 0, 0, 0);
+ 0, epd->bio_flags, bio_flags);
+ epd->bio_flags = bio_flags;
if (ret) {
set_bit(EXTENT_BUFFER_IOERR, &eb->bflags);
SetPageError(p);
@@ -3212,6 +3218,7 @@
.tree = tree,
.extent_locked = 0,
.sync_io = wbc->sync_mode == WB_SYNC_ALL,
+ .bio_flags = 0,
};
int ret = 0;
int done = 0;
@@ -3474,7 +3481,7 @@
if (epd->sync_io)
rw = WRITE_SYNC;
- ret = submit_one_bio(rw, epd->bio, 0, 0);
+ ret = submit_one_bio(rw, epd->bio, 0, epd->bio_flags);
BUG_ON(ret < 0); /* -ENOMEM */
epd->bio = NULL;
}
@@ -3497,6 +3504,7 @@
.get_extent = get_extent,
.extent_locked = 0,
.sync_io = wbc->sync_mode == WB_SYNC_ALL,
+ .bio_flags = 0,
};
ret = __extent_writepage(page, wbc, &epd);
@@ -3521,6 +3529,7 @@
.get_extent = get_extent,
.extent_locked = 1,
.sync_io = mode == WB_SYNC_ALL,
+ .bio_flags = 0,
};
struct writeback_control wbc_writepages = {
.sync_mode = mode,
@@ -3560,6 +3569,7 @@
.get_extent = get_extent,
.extent_locked = 0,
.sync_io = wbc->sync_mode == WB_SYNC_ALL,
+ .bio_flags = 0,
};
ret = extent_write_cache_pages(tree, mapping, wbc,