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Date: Fri, 15 Feb 2008 20:16:37 +0100
Subject: rewrite very slow
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Hello,

I need some help to tunning my storage.

Very simple test at begin (perl script test.pl):

#!/usr/bin/perl

$time=time();
for ($i=1;$i<100;$i++)
{
open (SUBOR,">$i.txt");
print SUBOR "aaaaaaaaaaaaaaaaaaa\n";
close (SUBOR);
print "WRITE $i. FILE\n";
}
$time2=time();
$rozdiel_casov=$time2-$time;

print "TIME ".$rozdiel_casov." sekund\n";

First run:
file1:/mnt/hosting/test# ./test.pl
WRITE 1. FILE
WRITE 2. FILE
...
WRITE 98. FILE
WRITE 99. FILE
TIME 0 sekund


Every next run (rewrite existing files) is very very very slow:

file1:/mnt/hosting/test# ./test.pl
WRITE 1. FILE
WRITE 2. FILE
...

WRITE 98. FILE
WRITE 99. FILE
TIME 43 sekund


I try it on ext3. Every run is only 1-3seconds.

I tried tunning my storage.
My last mount specification: 

(rw,noatime,nodiratime,nobarrier,osyncisosync,logbsize=256k,logbufs=8,quota)
I tried all possible configuration (barrier, nobarrier, osyncisosync,
logbssize=XX,logbufs=2-8) nothing help me.

file1:/mnt/hosting/test# xfs_info /mnt/hosting/
meta-data=/dev/mapper/vghosting-hosting isize=256    agcount=32,
agsize=7626752 blks
         =                       sectsz=512   attr=2
data     =                       bsize=4096   blocks=244056064,
imaxpct=25
         =                       sunit=0      swidth=0 blks, unwritten=1
naming   =version 2              bsize=4096
log      =internal               bsize=4096   blocks=32768, version=2
         =                       sectsz=512   sunit=0 blks
realtime =none                   extsz=65536  blocks=0, rtextents=0

I test it on 4 other xfs storages and results was similar.


Any ideas?

Thanks.

Dusan