Subject: Re: Limiting memory usage of bufcache?
To: Oleg Polianski <Oleg.Polianski@clear.co.nz>
From: Jukka Marin <firstname.lastname@example.org>
Date: 08/22/2001 09:20:58
On Wed, Aug 22, 2001 at 06:12:31PM +1200, Oleg Polianski wrote:
> Actually, if I'm not mistaken, the real reason is not the buffer cache
> itself but buffer pool that is used for metadata storing. The problem is
> that it cannot grow dynamically and its size is fixed and calculated during
> the system startup procedure based on the BUFCACHE option inside `bufinit'
> kernel subroutine (`/sys/kern/vfs_bio.c'). So, the real I/O thrashing
> usually is caused by relatively small or, probably, not very effective
> buffer pool management.
Well, the problem I'd like to fix somehow is that all my processes get
paged out of RAM when I do lots of disk I/O. After a nightly backup,
switching to another window, de-iconifying Netscape etc. causes lots of
paging. My mouse pointer freezes, changing focus to a window takes
5...10 seconds etc.. and no "real" disk I/O should occur in these cases,
it's all paging.
(I was making a cd and couldn't switch the windows because I was afraid
of saturating the SCSI disk and corrupting the cd.. It would help if I
had a separate disk for swap, but it would _still_ be paging like crazy.)