Re: After reboot fs with barrier faster deletes then fs with nobarrier

Szabolcs Illes
2007-06-27T22:18:57Z

On Wed, 27 Jun 2007 22:45:06 +0100, Chris Wedgwood <cw@f00f.org> wrote:

> On Wed, Jun 27, 2007 at 06:58:29PM +0100, Szabolcs Illes wrote:
>
>> I repeated this test several times, same results. I made sure
>> nothing was running while I was doing the tests, cpu was idle, hdd
>> led was not on, etc.
>
> instead of doing a reboot can you try something like:
>
> echo 1 > /proc/sys/vm/drop_caches
>
> or
> echo 3 > /proc/sys/vm/drop_caches
>
> (the value is a bit mask, bit 0 will drop the page cache, bit 1 will
> drop the slab)
>
> does that give you more or less the same results as rebooting?
yes it does.
>
>
>
>
> another thing to try, before the delete, also try:
>
> find path/to/whatever -noleaf >/dev/null
>
> and see if that helps (i expect it should greatly)
It doesn't help to much, see the updated tests:

mount opts: rw,noatime,nodiratime,logbsize=256k,logbufs=2

illes@sunset:~/tmp> tar xjf ~/Download/linux-2.6.21.5.tar.bz2 && sync &&
reboot

After reboot:
illes@sunset:~/tmp> time rm -rf linux-2.6.21.5/

real 0m28.127s
user 0m0.044s
sys 0m2.924s

illes@sunset:~/tmp> tar xjf ~/Download/linux-2.6.21.5.tar.bz2 && sync
illes@sunset:~/tmp> time rm -rf linux-2.6.21.5/
real 0m14.872s
user 0m0.044s
sys 0m2.872s

illes@sunset:~/tmp> tar xjf ~/Download/linux-2.6.21.5.tar.bz2 && sync
sunset:~ # echo 1 > /proc/sys/vm/drop_caches
illes@sunset:~/tmp> time rm -rf linux-2.6.21.5/

real 0m28.257s
user 0m0.036s
sys 0m2.732s

illes@sunset:~/tmp> tar xjf ~/Download/linux-2.6.21.5.tar.bz2 && sync
sunset:~ # echo 3 > /proc/sys/vm/drop_caches
illes@sunset:~/tmp> time rm -rf linux-2.6.21.5/

real 0m28.155s
user 0m0.048s
sys 0m2.772s

illes@sunset:~/tmp> tar xjf ~/Download/linux-2.6.21.5.tar.bz2 && sync
sunset:~ # echo 3 > /proc/sys/vm/drop_caches
illes@sunset:~/tmp> find linux-2.6.21.5/ -noleaf >/dev/null
illes@sunset:~/tmp> time rm -rf linux-2.6.21.5/

real 0m25.702s
user 0m0.064s
sys 0m2.664s

-------------------------------------------------------------------
mount opts: rw,noatime,nodiratime,logbsize=256k,logbufs=2,nobarrier

illes@sunset:~/tmp> tar xjf ~/Download/linux-2.6.21.5.tar.bz2 && sync &&
reboot
After reboot:

illes@sunset:~/tmp> time rm -rf linux-2.6.21.5/

real 1m12.738s
user 0m0.032s
sys 0m2.548s

illes@sunset:~/tmp> tar xjf ~/Download/linux-2.6.21.5.tar.bz2 && sync
illes@sunset:~/tmp> time rm -rf linux-2.6.21.5/

real 0m7.884s
user 0m0.028s
sys 0m2.008s

illes@sunset:~/tmp> tar xjf ~/Download/linux-2.6.21.5.tar.bz2 && sync
sunset:~ # echo 1 > /proc/sys/vm/drop_caches
illes@sunset:~/tmp> time rm -rf linux-2.6.21.5/

real 1m15.367s
user 0m0.048s
sys 0m2.264s

illes@sunset:~/tmp> tar xjf ~/Download/linux-2.6.21.5.tar.bz2 && sync
sunset:~ # echo 3 > /proc/sys/vm/drop_caches
illes@sunset:~/tmp> time rm -rf linux-2.6.21.5/

real 1m16.043s
user 0m0.060s
sys 0m2.448s

illes@sunset:~/tmp> tar xjf ~/Download/linux-2.6.21.5.tar.bz2 && sync
sunset:~ # echo 3 > /proc/sys/vm/drop_caches
illes@sunset:~/tmp> find linux-2.6.21.5/ -noleaf >/dev/null
illes@sunset:~/tmp> time rm -rf linux-2.6.21.5/

real 1m7.856s
user 0m0.044s
sys 0m2.020s

Cheers,
Szabolcs