On 12/08/2010 04:44 PM, Andreas Dilger wrote:
On 2010-12-08, at 14:07, Eric Sandeen wrote:
On 12/08/2010 01:01 PM, Andreas Dilger wrote:
I think an important factor here is that this is being tested on a
ramdisk, and is likely CPU bound, so any CPU reduction will directly
be measured as a performance improvement. Probably oprofile is in
order to see where other major CPU users are.
Yep, I ran oprofile.
samples % app name symbol name
1140046 41.8702 ext2.ko ext2_find_entry
1052117 38.6408 ext2.ko ext2_add_link
98424 3.6148 vmlinux native_safe_halt
40461 1.4860 vmlinux wait_on_page_read
29084 1.0682 vmlinux find_get_page
pretty slammed on those 2 ext2 functions! I think it's pretty
overwhelmed by the linear search.
Can you test ext4 with nojournal mode, but with dir_index enabled? I suspect that testing ext2 for directory performance is pointless. My personal threshold for ext2 directories was 10k files before I considered it a lost cause, and all of your tests are with 10k+ files per directory.
Just another log on the fire beneath getting rid of ext2 (and eventually ext3) in favour of ext4, IMHO. I'd be surprised if there are many benchmarks that ext2 can beat ext4 in nojournal mode, if allowed to enable "reversible" format changes like dir_index, uninit_bg, etc.
Cheers, Andreas
If we could get rid of ext2 (and eventually ext3), it would actually help reduce
the testing matrix and possibly let us invest even more in testing ext4. Having
to maintain three very similar code bases and test them all for correctness and
performance is a real pain :)
ric
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
