Swap space deallocation speed.

Dave Mielke (dave@mielke.cc)
Wed, 2 May 2001 23:15:35 -0400 (EDT)


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Ever since I've upgraded to the 2.2.17-14 i386 kernel as provided by RedHat,
I've had several hard crashes. One allowed "/var/log/messages" to be synced, so
I was able to capture those details (which are attached to this message as the
file "crash.log"). Once, instead of crashing, the system stayed up but all of
the respawn processes in "/etc/inittab" began to respawn to rapidly, I couldn't
create a shell process to poke around, and the keyboard eventually became
unresponsive. The relevant line in the log, as you can find in the attached
"crash.log" file, appears to be:

Unable to handle kernel paging request at virtual address 00020024

My guess is that, for whatever reason, I may now be running out of swap space
fairly often. If this is true, then either my children have altered their usage
habits around the same time that I upgraded the kernel, or something about swap
space management has changed between the 2.2.16-3 and 2.2.17-14 kernels. To
this end, I've asked my children to be careful about not opening too many
windows at the same time, and the system now stays up longer but still, on
occasion, without requesting my permission, still goes down hard.

I've also been watching the amount of available swap space with the "free"
command. It predictably goes down quite quickly when a hog like netscape is
started, but, when that same application exits, the available swap space goes
back up very slowly. This would seem to make it very easy to inadvertently run
out of swap space, i.e. quitting and restarting an application still, without
the user realizing it, appears to be a bad thing to do because of the as yet
unreclaimed swap space which is still being counted.

Do any of you have any ideas? If I'm right about the slow reclamation of the
swap space, is there anything I can do, e.g. alter something in "/proc", to
speed up swap space reclamation?

Thanks.

-- 
Dave Mielke           | 2213 Fox Crescent | I believe that the Bible is the
Phone: 1-613-726-0014 | Ottawa, Ontario   | Word of God. Please contact me
EMail: dave@mielke.cc | Canada  K2A 1H7   | if you're concerned about Hell.

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