Linux-kernel mailing list archive 1999-23,: v2.2.X[-andrea,-ac] -series scheduling problems.

# v2.2.X[-andrea,-ac] -series scheduling problems.

Jakob Sandgren (jakob@southpole.se)
Mon, 7 Jun 1999 19:53:44 +0200

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Hello,

The problem described below has been verified on:
2.2.5 (redhat "default" smp kernel)
2.2.9
2.2.9-andrea3
2.3.5-andrea3

2.0.37pre12 (+egcs patches) does however work (the performance is not
good but at least the OS is multitasking....)

Well now the problem;

When one process access the disk _a lot_, other processes seem to be
looked for several seconds (minutes) if they try to access the disk.

The following scenario is reproducable:

1. (VT #1) run: "mke2fs -i32768 -m0 /dev/sda9"
(wait 10 seconds)
2. (VT #2) run: ls -R /

Sometimes the ls command does not "start" until the mke2fs is
finished. Somethimes it lists just a few dirs. while mke2fs is
running.
Strace shows that all calls to function like; "lstat", "getdents"
etc. locks the process. If the information is cached, then everything
works ok.

This problem can be reproduced with other commands than mke2fs. Trying
to log in while dd:ing a 2GB file, have resultet in "login timeout"
several times.

Some information about the hardware:
Dual PIII/500, 512MB RAM, 4 disks in a hardware RAID-5 (64MB cache).
The hardware raidcontroller is an ICP-vortex (GDT6528RD).

_I_ did not find any big diffrence in the driver when comparing the
2.0 and 2.2 code.

Regards
/Jakob

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