Subject: change BUFPAGES warnings in sys/ufs/lfs/lfs_vfsops.c ?
To: None <tech-kern@NetBSD.org>
From: Jeff Rizzo <riz@NetBSD.org>
Date: 11/12/2005 15:38:17
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Bear with me on this; I don't pretend to understand the buffer cache in
any kind of detail at all, I'm just trying to figure out what changes I
should make to my system, and perhaps suggest changing the warnings.
I have an LFS volume on one of my dev boxes, and the other day I noticed
lfs_mountfs: entire ifile of length 5431296 cannot fit in 4987520 buffer
lfs_mountfs: please consider increasing BUFPAGES to at least 4880
... upon poking around a bit, I learned a little about our buffer cache,
and if I understand things correctly, I could achieve the goal
(increasing LFS_MAX_BYTES, which is defined in terms of bufmem_lowater)
by increasing vm.bufmem_lowater to a value that would make LFS_MAX_BYTES
greater than or equal to the ifile length of 5431296 (from the message
above), and possibly increasing vm.bufmem_hiwater to 4880*hw.pagesize
.... all using sysctl, and avoiding needing to hardcode a value in my
There are a number of other tests in sys/ufs/lfs/lfs_vfsops.c which
recommend changing BUFPAGES... should these be changed? If they were
changed, should they recommend changing vm.bufmem_hiwater,
vm.bufmem_lowater, or both?
If I'm missing anything important here (which is certainly likely),
please let me know so I can learn. :)
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