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Date:      Thu, 04 May 2000 13:53:58 -0500
From:      Steve Kaczkowski <steve@inc.net>
To:        freebsd-smp@freebsd.org
Subject:   General slowness with SMP
Message-ID:  <3911C746.AE662230@inc.net>

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Hey all!

Here's my setup:

Intel N440BX MB
Dual P3 550Es @ 550
1 gig of RAM
Using built in Symbios 875 SCSI
Mylex DAC960SX External RAID controller
Dual IBM 18ES (18 gig) UltraWide (Mirrored)
Running 4.0 Current (Was Release, but didn't matter. See below)
Cricket,RRDtool,ModPerl 5, Apache 1.3.9

Ok, here's the situation. This box is setup to be a statistics
collector using Cricket and RRDtool to pool routers,other
boxes,etc,etc. 

Running in dual mode we'd notice all sorts of sluggish behavior like:

Compile times on the Cricket database (basically perl just parsing
the config tree and making a DB file) would climb and climb. A
650 target database was taking about 70-80 seconds (Refer to Single
mode down below for more detail).

When using things like VI there would be pauses when initially opening
the file for editing. We'd also see pauses in the middle of editing
a file, moving around,tabbing,etc.

Pauses when untarring

Umm.. Overall memory usage is fine, have about 730megs free, no swap.
Everything
seems to be ok...

One thing I noticed is that when I'm doing a database compile (didn't
take note
of other processes like VI) is that the tasks will keep swapping back
and forth
between processors, seems to me that in itself would cause some speed
issues.

Anyway, no thinking this could be some sorta of strange SMP issue and
decided
to compile a single processor kernel to test the theory. Low and behold
everything
is working like a charm!

Database compiles take about 8 seconds instead of 60-80!

NO VI pauses

Untarring is fine

Everything is looking peachy..

Oh, I also tried CVS'n to Current with an SMP kernel which yielded the
same
results..

So the question is, what gives? I'm thinking that having tasks swapping
processors
isn't good in itself, but is there something else going on like file
locking
or some lower level processor locking issue that I don't know about?

From looking around the forums it seems that people are having really
good luck
with SMP boxes, so I must be doing something totally wrong!?

This is pretty much my first dive into FreeBSD SMP so I'm really not
sure
where or what to look at to help track this down and fix it..

Looking for any and all info...

Thanks in advance!


-- 
Steve Kaczkowski	Time Warner Telecom IDD
steve@inc.net          	(414)908-9012
http://www.inc.net     	(603)737-9209 Fax


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