SMP Strangeness

[Brett Worth]

I've just run some very rudimentary performance testing on a server in our
office and see some poor SMP results.  Can anyone suggest why?

Kernel: 2.4.18
Disk: Ultra Wide SCSI on AIC7XXX
CPUs: 2 x 700Mhz PIII
MB: Intel L440GX+
RAM: 4 x 64Mb = 256M

I'm just doing kernel compiles and timing them.

time (make -jN dep; make -jN clean; make -jN ; make -jN module; ; make -jN install ; make -jN modules_install)

N=1	264.79s real   251.83s user    20.74s system
N=2	304            502             46
N=3     402            660             53

Is this a memory bandwidth problem?  The machine is otherwise idle.  I also
ran the same command (j1) once before starting incase the cache made any
difference.

BTW:
# hdparm -T -t /dev/sda

/dev/sda:
 Timing buffer-cache reads:   128 MB in  0.79 seconds =162.03 MB/sec
 Timing buffered disk reads:  64 MB in  4.12 seconds = 15.53 MB/sec


Brett

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