Compaq/XENIX Disk slow

[Stephen Ayers]

I have a Compaq 386 Deskpro model 40 that appears to run dog slow.
I am in the process of upgrading the memory which should make a 
significant difference.  I am wondering what else I may be able to
improve I/O performance through hardware and software tuning.

Some more background, a couple of months ago I replaced my Compaq
40MB disk drive when it went belly-up.  Of course the system was no
longer under warranty and since Compaq wanted $3600 for a replacement
80MB drive I looked elsewhere.

The solution that I came up with was to replace the disk with a
Seagate 4096 and too add a WD1006WA2 controller to drive it.  I left
the Compaq controller in to drive the floppy since the WD controller
didn't seem to want anything to do with it.

Things work ok, but seem to run slow.  For example a dd of the XENIX
partition (68MB) to /dev/null takes 7:22 wall time.  While dd
is running the system will not respond to commands on any other
screens.  Interupts seem to be the problem.  Here is vmstat
output while dd is running:

    procs  	       paging                              system        cpu
 r  b  w  si  so  ch  cm ffr swr sww rec shf shc cpy  pf  in   sy  cs  us su id

 3 13  1   0   0   0   0   0   0   0   0   0   0   0 162 312  316 157   0 48 52
 2 14  1   0   0   0   0   0   0   0   0   0   0   0 163 315  319 157   0 33 67
 3 14  0   0   0   0   0   0   0   0   0   0   0   0 159 308  309 154   3 35 62
 3 14  0   0   0   0   0   0   0   0   0   0   0   0 126 249  241 120   2 25 73
 2 15  0   0   0   0   0   0   0   0   0   0   0   0 167 321  326 162   3 42 55
 2 15  0   0   0   0   0   0   0   0   0   0   0   0 169 318  323 160   1 44 55

The interupts per second and the system time look high to me for
simply reading the disk sequentually.

When I purchased the WD controller I was told it was 1:1 interleaf
and DMA.  Given the interupt level and the system startup messages
I doubt DMA is being used.  Here is a copy of the system startup
messages:

	SysV release 2.3.1 kid 5.34 for i80386 Serial Number: scoxxxxx

10 bits of I/O address decoding
Sun Jun 25 12:16:27

device    address	vector	dma	comment
----------------------------------------------------------------------------
%floppy   0x3F2-0x3F7	06	2	unit=0 type=96ds15
%serial   0x3F8-0x3FF	04	-	unit=0 type=Standard nports=1
%serial   0x2F8-0x2FF	03	-	unit=1 type=Standard nports=1
%parallel 0x3BC-0x3BE	07	-	unit=1
%parallel 0x278-0x27A	05	-	unit=2
%tape     0x2C0-0x2C4	05	1	type=W
%console  -		-	-	unit=cga type=4
%disk     0x1F0-0x1F7	36	-	type=W0 unit=0 cyls=1024 hds=9 secs=17
rootdev 1/40, pipedev 1/40, swapdev 1/41
mem: total = 1024k, reserved = 4k, kernel = 636k, user = 384k
kernel: drivers = 4k, 4 screens = 20k, 200 i/o bufs = 200k, msg bufs = 8k
nswap = 5000, swplo = 0, Hz = 50, maximum user process size = 2884k

---------------------------------------------------------------------

You will notice %disk entry does not list anything in the DMA column.

Does anyone know if this controller can support DMA or if XENIX
will?  How about a controller that will?

Any suggestions on system tuning paramaters that might also improve
system thoughput would be greatly appreciated.

Thanks in advance!


-- 
Steve Ayers, Atex, Inc., A Kodak Company
{sun,ll-xn,kodak}!atexnet!sda
+1 617 276-7384