Unexpected slowness *getting desperate*

zaanpenguin · Apprentice Joined: 01 Jul 2003 Posts: 203

Actors:

Intel Pentium-4 2.8GHz HT
2x512MB DDR in dual channel mode
ASUS P4P800-VM
2x80GB IDE Maxtor 5400RPM (PM&PS in RAID1)
Liteon 52x/32x/52x (SM)

Stage:

1 2U 19" Rackmount, 3 Casefans (2 generating airflow over mainboard, 1 over harddisks)

Scene:

During compiles and other CPU intensive tasks, the machine is experiencing a massive slowdown (most of the time & to 486-like speeds). It does this at random times and sometimes it will speed up a little again. At first I thought this was a heat problem, but the heatsink only feels lukewarm and the CPU fan is blowing air only slightly warmer. Also, if I kill the machine during a compile and/or slowdown and immediately jump to the BIOS, the CPU temperature registers at 45-50 degrees and the mainboard never gets above 25 degrees. Then I thought this was related to a SMP/HyperThreading problem. However, when I run a single thread compile on a UP kernel, I still get these weird slowdowns. I'm really at a complete loss at what could possibly cause this. There are no errors in the kernel or system logs at all. The harddisks don't experience the slowdowns either.
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avendesora · Posted: Thu May 13, 2004 2:58 pm Post subject:

It sounds reasonable that your machine doesn't react
just as fast when you are eating 100% CPU than when
it's idle...

What exactly is slowing down during those compiles?

Jarhead · Guru Joined: 26 Mar 2004 Posts: 474

Have you tried prelinking? Its worked miracles for me and my Inspiron 1100 :-D

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Rainmaker · Posted: Thu May 13, 2004 11:40 pm Post subject:

maybe run a memtest86?

Although it does sound more like a processor problem...

What does "top" show during compiles? What's eating your CPU and memory?

What are your MAKEOPTS? Did you use -j3, or just -j?
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If you can't dazzle them with brilliance, baffle them with bullshit.

Odin · Tux's lil' helper Joined: 04 Mar 2003 Posts: 92

Are you sure you've got DMA enabled for your drives?

Thats the only thing I've seen cause *massive* slowdowns during compiles.

zaanpenguin · Apprentice Joined: 01 Jul 2003 Posts: 203

Unbelievable, but I've found the problem. The BIOS sets incorrect MTRRs due to the use of the onboard VGA card. All one needs to do is reset the MTRRs properly. This problem does not occur if you use a video card in the AGP slot of the motherboard. If you have this motherboard and are experiencing the same problem, drop me a line and I'll help you out.
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Staying crunchy even in milk!