Very poor performance with 2.6.4

[Andreas Hartmann <andihartmann@freenet.de>]

Hello!

I tested kernel 2.6.4. While compiling kdelibs and kdebase, I felt, that
kernel 2.6 seems to be slower than 2.4.25.

So I did some tests to compare the performance directly. Therefore I
rebooted for everey test in init 2 (no X).

I locally compiled 2.6.5rc2 3 times under 2.6.4 and under 2.4.25 on a
reiserfs LVM partition, which resides onto a IDE HD (using DMA) and got
the following result:

In the middle, compiling under kernel 2.6.4 tooks 9.3% more real time than
under 2.4.25.
The user-processortime is about the same, but the system-processortime is
under 2.6.4 32.9% higher than under 2.4.25.


Now, I switched off preemption. But the performance isn't much better:
8.8% (9.3% with preemption) more real-time compared to 2.4.25 and 28%
(32.9% with preepmtion) more system-time.



Does anybody know, how to get the same performance under 2.6.4 (or even
better) as under 2.4.25?


My hardware:
AMD Athlon(tm) XP 2000+

00:00.0 Host bridge: VIA Technologies, Inc. VT8366/A/7 [Apollo KT266/A/333]
00:01.0 PCI bridge: VIA Technologies, Inc. VT8366/A/7 [Apollo KT266/A/333 AGP]
00:09.0 Ethernet controller: Silicon Integrated Systems [SiS] SiS900
10/100 Ethernet (rev 02)
00:0c.0 Ethernet controller: Intel Corp. 82557/8/9 [Ethernet Pro 100] (rev 0c)
00:10.0 USB Controller: VIA Technologies, Inc. USB (rev 80)
00:10.1 USB Controller: VIA Technologies, Inc. USB (rev 80)
00:10.2 USB Controller: VIA Technologies, Inc. USB (rev 80)
00:10.3 USB Controller: VIA Technologies, Inc. USB 2.0 (rev 82)
00:11.0 ISA bridge: VIA Technologies, Inc. VT8235 ISA Bridge
00:11.1 IDE interface: VIA Technologies, Inc.
VT82C586A/B/VT82C686/A/B/VT8233/A/C/VT8235 PIPC Bus Master IDE (rev 06)
00:11.5 Multimedia audio controller: VIA Technologies, Inc. VT8233/A/8235
AC97 Audio Controller (rev 50)
01:00.0 VGA compatible controller: ATI Technologies Inc Rage 128 PF/PRO
AGP 4x TMDS


Regards,
Andreas Hartmann