12x performance drop on md/linux+sw raid1 due to barriers [xfs]

[Justin Piszcz]

On Thu, 11 Dec 2008, Justin Piszcz wrote:

>
>
> On Wed, 10 Dec 2008, Bill Davidsen wrote:
>
>> Justin Piszcz wrote:
>>> Someone should write a document with XFS and barrier support, if I recall,
>
>

Best not to do things in a rush, here is the correct benchmark:

# rm -rf linux*7
# sync
# echo 1 > /proc/sys/vm/drop_caches
# /usr/bin/time bash -c 'tar xf linux-2.6.27.7.tar; sync'
0.13user 1.62system 0:46.67elapsed 3%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (17major+955minor)pagefaults 0swaps

Justin.