mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-06 19:08:57 +09:00
f942e47453
[ Upstream commit 374d45af6435534a11b01b88762323abf03dd755 ]
Whenever we issue a command we allocate a path and then compute it. For
the current inode this is not necessary since we have one preallocated
and computed in the send context structure, so we can use it instead
and avoid allocating and freeing a path.
For example if we have 100 extents to send (100 write commands) for a
file, we are allocating and freeing paths 100 times.
So improve on this by avoiding path allocation and freeing whenever a
command is for the current inode by using the current inode's path
stored in the send context structure.
A test was run before applying this patch and the previous one in the
series:
"btrfs: send: keep the current inode's path cached"
The test script is the following:
$ cat test.sh
#!/bin/bash
DEV=/dev/nullb0
MNT=/mnt/nullb0
mkfs.btrfs -f $DEV > /dev/null
mount $DEV $MNT
DIR="$MNT/one/two/three/four"
FILE="$DIR/foobar"
mkdir -p $DIR
# Create some empty files to get a deeper btree and therefore make
# path computations slower.
for ((i = 1; i <= 30000; i++)); do
echo -n > "$DIR/filler_$i"
done
for ((i = 0; i < 10000; i += 2)); do
offset=$(( i * 4096 ))
xfs_io -f -c "pwrite -S 0xab $offset 4K" $FILE > /dev/null
done
btrfs subvolume snapshot -r $MNT $MNT/snap
start=$(date +%s%N)
btrfs send -f /dev/null $MNT/snap
end=$(date +%s%N)
echo -e "\nsend took $(( (end - start) / 1000000 )) milliseconds"
umount $MNT
Result before applying the 2 patches: 1121 milliseconds
Result after applying the 2 patches: 815 milliseconds (-31.6%)
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Stable-dep-of: 005b0a0c24e1 ("btrfs: send: use fallocate for hole punching with send stream v2")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.