[problem] RH 2.4.7-2 kernel slows to a crawl under heavy i/o

[Jeff Busch]

machine:  Compaq Proliant DL360 w/4GB mem, dual 36GB SCSI drives
OS:	    RedHat 7.1 + errata updates, kernel-enterprise-2.4.7-2.i686.rpm from
'Roswell 2'

Under heavy I/O (Apache and a custom C++ module which do lots of mmap and
munmap calls over large data sets - 7GB total), the machine slows to a
crawl.  The problem persists even after live traffic to the machine ceases.
A top listing shows both cpu's at 100% system.  Any commands (ps, uname,
whatever) take minutes to return results.

The same setup on RH 6.2 with 2.4.3-ac3 works fine.  Please let me know what
information may be useful to debugging this problem (no oops yet), and other
kernels to try; I'm looking at 2.4.8-ac9 right now.

Thanks,
Jeff Busch
System Administrator
Half.com - an eBay company