From: julian@tfs.com (Julian Elischer)
Subject: Re: [386bsd] Queries for the new scsi driver.
Organization: TRW Financial Systems
Date: Wed, 6 Jan 1993 20:02:35 GMT

In article <3813@tansei1.tansei.cc.u-tokyo.ac.jp> mhiroshi@tansei.cc.u-tokyo.ac.jp (H. Murakami) writes:
>To: comp.unix.bsd
>Subject: [386bsd] Queries for the new scsi driver.
>
>I tried the Julian new scsi driver.
>
>However, before I use the aha1542 specific new-scsi driver,
>I was able to use two partition on one disk drive for the swap like:
>
>	config   "386bsd"    root on as0 swap on as0b and as0e
>
>And both as0b and as0e were working fine even they are on the identical drive.
>
>After I put the new scsi driver,
>in the configuration file for the kernel, 
>I removed many unused drivers to save the kernel size 
>by commenting out like:
>
>	#options 	NFS
>	#disk 	wd1 	at wd0 drive 1
>	#device we0 at isa ....
>	#device ne0 at isa ..
>	#device ec0 at isa ..
>	#device is0 at isa ..
>	#pseudo-device ddb
>
>for the swap partition I made the line like:
>
>	config   "386bsd"    root on sd0 swap on sd0b and sd0e
>
>My current problem with this julian new scsi driver system is,
>
>the kernel built does not add the partition sd0e for the swap area. 
>The "swapon /dev/sd0e" makes error message saying that 
>	
>	adding swap: failed! (unchanged)
>	swapon: /dev/sd0e Device not configured

did you modify the devices.i386 file in i386/conf?

>
>Note, I have the line in the file /etc/fstab like:
>
>	/dev/sd0e - swap sw - -
>
>This kind of trouble never happened when I used the old scsi driver.
>What is the reason that I cannot assign /dev/sd0e  for swap ?

my guess is that you haven't done the full configuration..

>
>You might think that I should not use two swap reagion on one drive,
>however I have a good reason for that.
>Sometimes, I just use /dev/sd0b of size 50MB for the swap, and
>/dev/sd0e of size 1.0GB for the file system by using newfs
>to work with many files.
>And sometimes I would like to use both /dev/sd0b and /dev/sd0e to
>enable the large virtual memory as large as a giga bytes.
>(However I find many trouble to extend the virtual memory of that
>size or a few hundred meg, I still making struggle for that.)

that is a good reason..
I have done similar.
>
>BTW.
>	What is the advantage of the new scsi driver 
>	compared the old scsi drivers ?
>	Was the old scsi driver not using DMA transfer
>	but program data transfer?

both use dma,
however the new drivers are modular, allowing the easy addition of extra
devices. They also support multiple different types of controllers.
The performance is much the same (disk writes get 20% faster), but 
the ease of modification and tayloring makes it easier
to add new devices.
the following adapteres 'fit into' the system.

aha1542
aha1742
bt742a
tmc1670 (mostly works)
wd7000  (apparently mostly works)

I also have drivers for:
scsi disk
scsi tape
scsi cdrom
scsi media changer
scsi (kodak) scanner (can't release)
scsi (AEG) character recognition engine (can't release)
scsi (CALERA) character recognition engine (can't release)

All of the device drivers can run on any of the adapters without change
and I sometimes run them on multiple DIFFERENT cintrollers on the same bus
at the same time:
e.g.
  2 disk and 1 tape on a bt742
+ 1 disk and i AEG on a aha1742
+ 1 tape on a bt742

all at the same time.
The disk are sd0,sd1,sd2
the tapes are st0 and st1
and the AEG is bll0 and bll1 (it has 2 lu's)

try do that with the old scsi driver....


>	It seems the data transfer rate measured by the dd command
>		/usr/bin/time dd if=/dev/rsd0h of=/dev/null ibs=512x88
>	did not speed up compared with that of old scsi driver.
>	(comparision is made with only one swap partition system.
>	rsd0h is about 300MB large to reduce the effect of the caching.)
>	The jumper of the adaptec 1542b card is to use the syncronos
>	negotiation mode.
>	CPU is 486DX 33MHz, AMI bios 256K cache 16MB Dram, 
>	IDA card + adaptec 1542B.
>	The scsi disk is Fujitsu's 1.6GB, 11mS, 10MB/Sec peak, SCSI-2 disk.
>	It has 512bytes/sector, 88 sectors/track, and 90 rotation/sec means,
>	it the data transfer is made ideally, its sustained transfer rate
>	is about 4MB/sec, but dd give the number around 1MB/sec.

 If you use a EISA card, you will achieve around 3.2MB/sec. (with 16k reads)
 the aha1542 just doesn't seem that fast. I use the bustek 742 and the adaptec
 1742 for faster throughput. (On EISA only though)

>PS.
>	What is the meaning of the message given at the boot time by the
>	new scsi driver;
>
>		aha0 reading board settings, 150 nSEC ok, use 200 nSEC
>	** aha0 probing for scsi devices **
>	dev0,lu0: type 0(direct),fixed 'FUJITSU M2652S-512     008P' scsi2
>	sd0: 1651MB, cyls 1944, heads 20, secs 87, bytes/sec 512
>
>	Why it drops from 150 nS to 200nS (and what is the meaning of 150nS)?
>	Does this relate to the disk trasfer rate?
>
>		Hiroshi Murakami
>		mhiroshi@tansei.cc.u-tokyo.ac.jp
>		hiroshi@teine.chem2.hokudai.ac.jp

150ns is the first (highest) speed it could get the dma to work at.
it is only a small DMA test, so it might be marginal at that speed, so
it backs off to the next slower speed. The adaptec can actually use a 100nSec
setting but it crashes my machine when I try it so I start at 150Nsec.
You might make it start it's speed check at 100Nsec. If it works
then it will back down to 150Nsec rather than 200Nsec.

you may then try 'hard-wiring' to 100Nsec and stopping it from
backing down, but be on the look out for errors, as the test
at 100Nsec only transfers some 64 bytes (I think) so just because it
succeeds, doesn't mean that it will be reliable.

>
>PS2.
>	What is the virtue of ddb ?
>Sorry for the buggy English.
better than my japanese!


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