Read this and be ashamed ;) or: Awfull performance loss since 2.4.18 to 2.4.21-pre2

[Marc-Christian Petersen <m.c.p@wolk-project.de>]

Hi all,

not much to say about, just read. All are vanilla kernels w/o any patch.

/dev/hda5 on /home type ext3 (rw,data=ordered)
/dev/hda5             10080488    731488   8836932   8% /home

UDMA100 IDE Drive, DMA is on. All these runs were done right after bootup.
Mashine is a Celeron 1,3GHz, 512MB RAM, 512MB SWAP.

root@codeman:[/] # uname -r
2.4.18
root@codeman:[/] # dd if=/dev/zero of=/home/largefile bs=16384 count=131072
131072+0 records in
131072+0 records out
2147483648 bytes transferred in 119.140681 seconds (18024772 bytes/sec)
root@codeman:[/] # 

root@codeman:[/] # uname -r
2.4.19
root@codeman:[/] # dd if=/dev/zero of=/home/largefile bs=16384 count=131072 
131072+0 records in
131072+0 records out
2147483648 bytes transferred in 140.305836 seconds (15305733 bytes/sec)

root@codeman:[/] # uname -r
2.4.20
root@codeman:[/] # dd if=/dev/zero of=/home/largefile bs=16384 count=131072
131072+0 records in
131072+0 records out
2147483648 bytes transferred in 172.327570 seconds (12461637 bytes/sec)

root@codeman:[/] # uname -r
2.4.21-pre2
root@codeman:[/] # dd if=/dev/zero of=/home/largefile bs=16384 count=131072          
131072+0 records in
131072+0 records out
2147483648 bytes transferred in 177.743959 seconds (12081894 bytes/sec)


ciao, Marc