mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-05 02:19:51 +00:00
Btrfs: don't do nocow check unless we have to
Before we write into prealloc/nocow space we have to make sure that there are no references to the extents we are writing into, which means checking the extent tree and csum tree in the case of nocow. So we don't want to do the nocow dance unless we can't reserve data space, since it's a serious drag on performance. With the following sequence fallocate -l10737418240 /mnt/btrfs-test/file cp --reflink /mnt/btrfs-test/file /mnt/btrfs-test/link fio --name=randwrite --rw=randwrite --bs=4k --filename=/mnt/btrfs-test/file \ --end_fsync=1 we get the worst case scenario where we have to fall back on to doing the check anyway. Without this patch lat (usec): min=5, max=111598, avg=27.65, stdev=124.51 write: io=10240MB, bw=126876KB/s, iops=31718, runt= 82646msec With this patch lat (usec): min=3, max=91210, avg=14.09, stdev=110.62 write: io=10240MB, bw=212753KB/s, iops=53188, runt= 49286msec We get twice the throughput, half of the runtime, and half of the average latency. Thanks, Signed-off-by: Josef Bacik <jbacik@fb.com> [ PAGE_CACHE_ removal related fixups ] Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
parent
0f873eca82
commit
c6887cd111
1 changed files with 22 additions and 22 deletions
|
@ -1534,6 +1534,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
|
|||
reserve_bytes = round_up(write_bytes + sector_offset,
|
||||
root->sectorsize);
|
||||
|
||||
ret = btrfs_check_data_free_space(inode, pos, write_bytes);
|
||||
if (ret < 0) {
|
||||
if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
|
||||
BTRFS_INODE_PREALLOC)) &&
|
||||
check_can_nocow(inode, pos, &write_bytes) > 0) {
|
||||
|
@ -1548,16 +1550,14 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
|
|||
*/
|
||||
num_pages = DIV_ROUND_UP(write_bytes + offset,
|
||||
PAGE_SIZE);
|
||||
reserve_bytes = round_up(write_bytes + sector_offset,
|
||||
reserve_bytes = round_up(write_bytes +
|
||||
sector_offset,
|
||||
root->sectorsize);
|
||||
goto reserve_metadata;
|
||||
} else {
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
ret = btrfs_check_data_free_space(inode, pos, write_bytes);
|
||||
if (ret < 0)
|
||||
break;
|
||||
|
||||
reserve_metadata:
|
||||
ret = btrfs_delalloc_reserve_metadata(inode, reserve_bytes);
|
||||
if (ret) {
|
||||
if (!only_release_metadata)
|
||||
|
|
Loading…
Reference in a new issue