Mikhail Ramendik wrote:
Hello,
I have an computer with an AMD Duron, and the motehrboard chipset is VIA
KT133. The hard drive is a Seagate Barracuda 7200.7 ; no other EIDE
devices are attached.
I run an RH9-based distro, and added a 2.6.4 kernel to it. The following
problem was tested with two kernel variants: 2.6.4+wolk2/0 with
preeemption enabled, and 2.6.4 plain from kernel.org with preemption
disabled. No difference.
I noticed performance problems with 2.6.4, and tracked them to strange
HDD behavior.
It turned out that on disk-intensive operation, the "system" CPU usage
skyrockets. With a mere "cp" of a large file to the same direstory
(tested with ext3fs and FAT32 file systems), it is 100% practically all
of the time !
Which tool do you use for measure? xosview?
I'm having here the same problem. But it depends on the tool which is used for measuring. If I use top from procps 3.2, I can't see this high system load. "time" can't see it, too.
This is what top says during cp of 512MB-file:
Cpu(s): 2.0% us, 8.3% sy, 0.0% ni, 0.0% id, 89.0% wa, 0.7% hi, 0.0% si
New is "wa", what probably means "wait". This value is very high as long as the HD is writing or reading datas:
cp dummy /dev/null
produces this top-line:
Cpu(s): 3.0% us, 5.3% sy, 0.0% ni, 0.0% id, 91.0% wa, 0.7% hi, 0.0% si
and time says:
real 0m53.195s
user 0m0.013s
sys 0m2.124s
But you're right, 2.6.4 is slower than 2.4.25. See the thread "Very poor performance with 2.6.4" here in the list.