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

To: "Chris Wedgwood" <cw@xxxxxxxx>
Subject: Re: After reboot fs with barrier faster deletes then fs with nobarrier
From: "Szabolcs Illes" <S.Illes@xxxxxxxxxxxxxxxxx>
Date: Wed, 27 Jun 2007 23:18:50 +0100
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20070627214506.GA1352@xxxxxxxxxxxxxxxxxxxxx>
References: <op.tuldjrzef7nho5@xxxxxxxxxxxxxxxxxxxxx> <20070627214506.GA1352@xxxxxxxxxxxxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx
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On Wed, 27 Jun 2007 22:45:06 +0100, Chris Wedgwood <cw@xxxxxxxx> 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


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