DU 3.2G Tuning Questions

From: Gunther Feuereisen <gunther_at_ibm.net>
Date: Tue, 06 Oct 1998 16:02:29 +1000

Hi,

I'm currently looking at an Alpha 8200 running 3.2G/Oracle 7.1.6.2

The system has been set-up using gh-chunks, something I've never used before,
and I've just been reading through the tuning manual, and it contains the
following paragraph:

"For the best performance, the shared_mappers kernel variable should be
equal to the number of shared memory segments, and the
unshared_mappers, unaligned_attachers, and
unaligned_size_requests variables should be 0 (zero)."

Now, when I run dbx, two things happen:

Firstly:

--
# dbx -k /vmunix /dev/mem
dbx version 3.11.8
Type 'help' for help.
thread 0xfffffc00ec778000 stopped at  [thread_block:1934 ,0xfffffc000047aa58]
Source not available
warning: Files compiled -g3: parameter values probably wrong
(dbx)
--
Q: Can anyone explain what the warning message means?
--
(dbx) p *(vm_granhint_stats *)&gh_stats_store
struct {
    total_mappers = 389044
    shared_mappers = 0
    unshared_mappers = 389044
    total_unmappers = 398327
    shared_unmappers = 0
    unshared_unmappers = 398327
    unaligned_mappers = 0
    access_violations = 0
    unaligned_size_requests = 805
    unaligned_attachers = 54
    wired_bypass = 0
    wired_returns = 0
}
--
Q: Now according to the running kernel on this machine, the number of
shared_mappes
is zero, when for best performance it should be the same as total_mapers, and
unshared_mappers should be 0.
What effect (if any) is this having?
The gh-chunks setting is:
--
vm:
        gh-chunks=221
        vm-page-lock-count=128
--
Any help/thoughts appreciated ..
many thanks,
gunther

Received on Tue Oct 06 1998 - 06:05:58 NZDT