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| author | Liu Bo <bo.li.liu@oracle.com> | 2014-03-05 10:07:35 +0800 |
|---|---|---|
| committer | Josef Bacik <jbacik@fb.com> | 2014-03-10 15:17:19 -0400 |
| commit | 2131bcd38b18167f499f190acf3409dfe5b3c280 (patch) | |
| tree | 505aa099a705f6da3dec233c05fe0f827ff8cf84 /fs/btrfs/send.c | |
| parent | a4d96d6254590df5eb9a6ac32434ed9d33a46d19 (diff) | |
| download | lwn-2131bcd38b18167f499f190acf3409dfe5b3c280.tar.gz lwn-2131bcd38b18167f499f190acf3409dfe5b3c280.zip | |
Btrfs: add readahead for send_write
Btrfs send reads data from disk and then writes to a stream via pipe or
a file via flush.
Currently we're going to read each page a time, so every page results
in a disk read, which is not friendly to disks, esp. HDD. Given that,
the performance can be gained by adding readahead for those pages.
Here is a quick test:
$ btrfs subvolume create send
$ xfs_io -f -c "pwrite 0 1G" send/foobar
$ btrfs subvolume snap -r send ro
$ time "btrfs send ro -f /dev/null"
w/o w
real 1m37.527s 0m9.097s
user 0m0.122s 0m0.086s
sys 0m53.191s 0m12.857s
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Diffstat (limited to 'fs/btrfs/send.c')
| -rw-r--r-- | fs/btrfs/send.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 112eb647b5cd..646369179697 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -124,6 +124,8 @@ struct send_ctx { struct list_head name_cache_list; int name_cache_size; + struct file_ra_state ra; + char *read_buf; /* @@ -4170,6 +4172,13 @@ static ssize_t fill_read_buf(struct send_ctx *sctx, u64 offset, u32 len) goto out; last_index = (offset + len - 1) >> PAGE_CACHE_SHIFT; + + /* initial readahead */ + memset(&sctx->ra, 0, sizeof(struct file_ra_state)); + file_ra_state_init(&sctx->ra, inode->i_mapping); + btrfs_force_ra(inode->i_mapping, &sctx->ra, NULL, index, + last_index - index + 1); + while (index <= last_index) { unsigned cur_len = min_t(unsigned, len, PAGE_CACHE_SIZE - pg_offset); |