Description of problem:
- High iowait and cpu load w/ moderate disk io.  
- Similar to bug 129545 and bug121434, but critical difference 
  it that the system lacks RAID completely, but is still SMP.  
- Problem occurs if using either SMP or UP kernels listed below.
- during high iowait and lockup, kswapd is grabbing nearly all
  of the CPU

Version-Release number of selected component (if applicable):
kernel-smp-2.4.21-15.EL
kernel-smp-2.4.21-15.0.4.EL
kernel-smp-2.4.21-18.EL

System:
- Red Hat Enterprise Linux WS release 3 (Taroon Update 2); up2date
  current 2004/08/19
- ASLAB dual Athlon 1900; two IDE disks, separate channels.
- more info will be attached

How reproducible:
tar cf junk.tar /usr
watch top and feel the machine grind to a hault

Steps to Reproduce:
1.
2.
3.
  
Actual results:
machine grinds to hault and becomes unusable, or may crash completely

Expected results:
machine should not grind to hault with moderate disk io, should not
crash from moderate disk io.

Additional info:
- Temporary solution is to use Fedora Core 1: 
  kernel-smp-2.4.22-1.2199.nptl.athlon.rpm.
- tweaking a wide range of /proc/sys/vm/{min,max}-readahead failed
  to solve the problem