>>>
>>> Does anyone know how to build a version of the kernel that either does no disk
>>> cacheing (we have very fast RAID processors and SCSI disks on the machine) or
>>> limit the amount of cache that the system will allocate for disk?
Kelly,
we have a similar setup here (RH8 with latest bigmem kernel on a machine with 4GB ram and 1.4TB fs) and see a similar behaviour. Howevever, long ago I have accepted this as a "feature" of the linux kernel and I've yet to find that this causes any performance issues. It's true that if your file access is truly random caching the filesystem in RAM doesn't help, but I can't imagine that this is a significant performance hit. The system simply releases the cache as needed so that even if at any time you're seeing 100% memory usage, when a new process needs memory the RAM cache will give way.
I'm sure that there are ways to override this behaviour (see for instance the linux kernel hacking howto for hints) but I doubt that this is worth the effort unless you need to squeeze every last bit of performance out of your box. And if you do, I would suggest looking at installing a 2.6.x kernel instead.
-- Alberto
P.S. I found that in our case one thing that actually helped quite a bit with overall performance was tuning some kernel parameters for the particular raid controller we have (3ware IDE raid). I mention this because if you start going down the performance tuning path there are a number of things that you should look at.
************************************************************************** Alberto Accomazzi, NASA Astrophysics Data System http://ads.harvard.edu Harvard-Smithsonian Center for Astrophysics http://cfa-www.harvard.edu 60 Garden St, MS 31, Cambridge, MA 02138, USA [EMAIL PROTECTED] **************************************************************************
-- To unsubscribe or change options: http://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
