At Sun, 21 Jun 2009 13:32:02 -0400, "Greg A. Woods"
<woods%planix.com@localhost> wrote:
Subject: Re: more on the "vmmapva" kernel deadlocks on NetBSD-4
>
> Well, if it means anything my server lived through the night without any
> problems after rebooting with the BUFCACHE=5 kernel.
And now it's still chugging along happily:
$ uptime
4:34PM up 13 days, 4:11, 7 users, load averages: 0.14, 0.11, 0.37
I'm obviously not seeing quite as much "pages for cached file data" in
"systat buf" (rarely more than 70%), so a fair bit of RAM is being
wasted under the normal load profiles of this system, usually ~120MB but
that's not too bad on a system with 4GB I suppose, and it certainly
leaves lots of room for peak loads without needing any paging.
> Now to do some debugging and find out what the numbers actually are to
> see if I can code some reasonable heuristic for limiting BUFCACHE at
> boot automatically.
The coded I added to sys/i386/i386/pmap.c:pmap_bootstrap() does not work
because the code it calls (vfs_bio.c:buf_memcalc()) relies on the global
value of physmem to do its initial calculation.
Unfortunately on i386 it seems physmem isn't set soon enough. It is set
within the call to init386() in locore.S. init386() also calls
pmap_bootstrap(), but it does so before it calculates physmem.
I'm not sure if this can be reordered safely or not -- it seems that
other ports, notably alpha, mips, vax, and ia64 (though I'm not 100%
sure about mips), do calculate physmem before calling their
pmap_bootstrap().
So, as a test I moved the call to pmap_bootstrap() down below the
physmem calculations (I can't see any obvious interdependency that would
require the old order, turned on DEBUG_MEMLOAD for a wee extra peek into
things, and so far my test machine boots and runs just fine:
>> NetBSD/i386 BIOS Boot, Revision 3.3
>> (woods@once, Tue Jun 16 17:57:15 EDT 2009)
>> Memory: 617/2094976 k
Press return to boot now, any other key for boot menu
booting hd0a:netbsd - starting in 0
9381768+411940+376076 [443616+426273]=0xa88fd8
initial mem_cluster_cnt: 0
BIOS MEMORY MAP (8 ENTRIES):
addr 0x0 size 0x9a400 type 0x1
addr 0xf0000 size 0x10000 type 0x2
addr 0xfec00000 size 0x1400000 type 0x2
addr 0x7fee3000 size 0xd000 type 0x3
addr 0x7fee0000 size 0x3000 type 0x4
addr 0x9a400 size 0x5c00 type 0x2
addr 0x7fef0000 size 0x10000 type 0x2
addr 0x100000 size 0x7fde0000 type 0x1
final mem_cluster_cnt: 2
KVA space seems to be: 1057026048
buf_memcalc: bufcache is preset to 5%
buf_memcalc: bufmem calculated to be to 107274240 bytes
loading 0x7000-0x9a000 (0x7-0x9a)
loading 0xb91000-0x1000000 (0xb91-0x1000)
loading 0x1000000-0x7fee0000 (0x1000-0x7fee0)
kenter: 0x00002000
acpi: wakecode is installed at 0x2000, size=376
Loaded initial symtab at 0xc0ab4630, strtab at 0xc0b20eb4, # entries 26187
BIOS CFG: Model-SubM-Rev: fc-01-00, 0x74<EBDA,KBDINT,RTC,IC2>
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
2006, 2007
The NetBSD Foundation, Inc. All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
The Regents of the University of California. All rights reserved.
NetBSD 4.0_STABLE (GENERIC.MP) #10: Fri Jul 3 16:14:15 EDT 2009
woods@once:/rest/build/woods/once/netbsd-4-i386-i386-ppro-obj/rest/work/woods/m-NetBSD-4/sys/arch/i386/compile/GENERIC.MP
total memory = 2046 MB
rbus: rbus_min_start set to 0x80000000
avail memory = 1988 MB
buf_memcalc: bufcache is preset to 5%
buf_memcalc: bufmem calculated to be to 107274240 bytes
nbuf (bufhashtbl size) = 34920
Now maybe I should try this on the 4GB machine.... with bufcache set
back up to a higher number and then I can see if I can find some more
appropriate values to use for smarter auto-tuning....
(Maybe the copyright and build info prints should be moved up a bit too)
--
Greg A. Woods
Planix, Inc.
<woods%planix.com@localhost> +1 416 218-0099 http://www.planix.com/
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