Re: rawhide ext4/virtio FS performance hit (10x slower) ?
Josh Boyer wrote:
On Mon, May 7, 2012 at 8:43 AM, Jim Meyering <jim(a)meyering.net>
wrote:
> Today I noticed that some tests from coreutils' test suite
> were taking far longer than they used to on rawhide.
> For example, run this command in an empty directory:
>
> seq 200000|env time xargs touch
>
> it takes < 5s on F17 3.3.4-1.fc17.x86_64 ext4/sdb8/SSD, yet
> it takes 47s on rawhide 3.4.0-0.rc5.git5.1.fc18.x86_64 ext4/vda1/SSD
>
> 10x performance hit... ouch.
>
> Does anyone know why?
Rawhide has all the kernel debug options turned on. It isn't
worthwhile doing a comparison when those are enabled. You could try
again with the first -rc6 build that shows up, as that will have the
options disabled.
Hi Josh,
I've just rerun the test with 3.4.0-0.rc6.git1.1.fc18.x86_64,
and it takes just as long, so the hit is *not* due to debug options:
$ seq 200000|env time xargs touch
0.17user 41.98system 0:48.22elapsed 87%CPU (0avgtext+0avgdata 1424maxresident)k
88inputs+0outputs (0major+4502minor)pagefaults 0swaps