Re: [PATCH] Add ext3 data=guarded mode

[Amit Shah <amit.shah@redhat.com>]

On (Thu) Apr 16 2009 [15:42:01], Chris Mason wrote:
> Hello everyone,
> 
> Here's an updated (v4) patch for ext3 data=guarded mode.  The first two
> patches in the series are unchanged, and it looks like Linus pulled them
> in this morning.

I had written a small program that calculates the time needed to allocate
a file and zero it using various methods (posix_fallocate, mmap, 4k-chunk
writes, 8k-chunk writes). I did this on a 20G partition with each method
creating a file 4G in size. The system has 3G RAM. The program that does
this is at

http://fedorapeople.org/gitweb?p=amitshah/public_git/alloc-perf.git;a=blob;f=test-file-zero-alloc-speed.c;hb=HEAD

with the script to run it for the multiple filesystems at

http://fedorapeople.org/gitweb?p=amitshah/public_git/alloc-perf.git;a=blob;f=run_test.sh;hb=HEAD

I have a few results from those runs, time in seconds:

# 4GiB file, kernel b0cbc861a3c05e634520b049b5cc27ad6febb51f

filesystem	posix-fallocate	mmap	chunk-4096	chunk-8192
ext2		74		96	761		81
ext3-writeback	87		97	202		93
ext3-ordered	86		94	134		104
ext4		0		84	120		91
xfs		0		84	274		81
reiserfs	85		84	187		98
btrfs		0		86	121		85

# 4GiB file, kernel 9f76208c33984ab777eace5d07a4e36e88703e02 + ext3-guarded

filesystem	posix-fallocate	mmap	chunk-4096	chunk-8192
ext3-guarded	85		97	459		90
ext3-writeback	86		95	140		94
ext3-ordered	86		96	277		95
btrfs		0		81	499		93
xfs		0		79	184		84

These were with a desktop running with a few terminal sessions and one
konqueror session (to gauge the times a user will actually see while
working on her desktop).

Running the test in single user mode, I get the following results:

# 4GiB file, kernel 9f76208c33984ab777eace5d07a4e36e88703e02 + ext3-guarded

filesystem	posix-fallocate	mmap	chunk-4096	chunk-8192
ext3-guarded	84		86	163		91
ext3-writeback	84		88	217		91
ext3-ordered	84		86	226		91
btrfs		0		76	86		79
ext4		0		73	195		76

		Amit