[BL] scsi/smp 2.4.31 kernels
baslinux at lists.ibiblio.org
baslinux at lists.ibiblio.org
Sat May 10 18:44:16 EDT 2008
This is actually relevant to using BL on obsolete hardware. SCSI-2 (fast
wide) and SCSI-3 (ultra), a board (and a card) that do both. Circa 1997.
We were given several SCSI computers from that era this year.
>> Then I added SMP support (dual processor), which made it much larger. Then
>> PPP would not work (though the modules would insert - same problem with
>> 2.2.16 kernel) so I had to compile that into the kernel too, which brought
>> it up to about 800K.
The onboard SCSI stopped working but lilo is booting from SCSI drive
plugged into a SCSI card. SHIFT and CTRL do not work to choose between
OS'es like they did in an IDE setup (I can boot with DOS floppy disk to
change OS or kernel). The PPP kernel now crashes instead of dialing,
complaining about not finding something. SMP kernel should not be used
with add-in card to dial, apparently. It worked fine with onboard SCSI
for an hour or so (except for dmesg error messages and slow CD-ROM reads).
> The only use I found mentioned for SMP is to compile more kernels
> The HOWTO says:
> make bzImage MAKE="make -j3"
> to compile kernels faster with SMP system.
> Dual 450 is in theory not as fast as 900 for compiling kernels.
Today I compiled my small laptop kernel and timed it with standard kernel,
SMP kernel used normally, SMP -j3 and SMP -j (unlimited processes - use if
you have lots of memory or swap space).
The HOWTO said to time with
time -v sh -c 'make bzImage'
On this dual-PII 450 with SMP kernel 'time' told me (apart from using 101%
and 190% of cpu time for compiling without and with -j switch).
SMP -j3 377 sec
SMP -j 378 sec
SMP 369 sec
All about 6 minutes. This implies SMP slows down compiling.
non-SMP scsi kernel timed out at about 6 minutes on the clock
1.2GHz 143 seconds - 2.4 minutes ('time').
This is the opposite of what was expected.
The -j appeared to make things go faster, subjectively. So I timed these
again with a timer.
SMP -j3 2.5 minutes (roughly)
SMP -j 3.5 minutes
SMP 6 minutes
'time' is apparently not measuring actual time, but time it would have
taken without using 3 processes, so it is rather useless here.
People told me using the SMP kernel would not double my speed, maybe
increase it by 50-75% or even 90%. It has more than doubled the speed of
compiling a kernel and is comparable with using a 1.2GHz computer.
Both have lots of RAM. The 1.2GHz has PC133RAM, the dual-CPU PC100 RAM,
ditto for board bus speeds.
Conclusion: The HOWTO is wrong in two respects, and dual-cpu obsolete
scsi computers (or computers with scsi cards) work fine for BL except you
cannot dial with SMP kernel if you use an add-in card, or have a boot menu
choice with lilo. SMP kernel should be used only when compiling more
I think I had some problem with booting to DOS from a scsi drive plugged
into the card directly. I should try this again. lilo works fine if you
want the default OS and kernel.
Someone just gave us three more Win95 era computers left over from their
yard sale that should be perfect for BL. I am trading some tomato
seedlings. The computers did not sell for $5 and seedlings would cost
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