Date: 27 Sep 1999 23:40:37 -0400 From: Kevin Street <street@iname.com> To: "Kenneth D. Merry" <ken@kdm.org> Cc: groudier@club-internet.fr (Gerard Roudier), scsi@FreeBSD.ORG Subject: Re: sym driver 0.3.0 Message-ID: <874sgfog96.fsf@mired.eh.local> In-Reply-To: "Kenneth D. Merry"'s message of "Mon, 27 Sep 1999 13:56:09 -0600 (MDT)" References: <199909271956.NAA38933@panzer.kdm.org>
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"Kenneth D. Merry" <ken@kdm.org> writes:
> Gerard Roudier wrote...
> > You test is not serious. If you only can provide 1.5MB/second throughput
> > for a benchmark of SCSI driver, please go away or make comparison with an
> > AHA 1542. I consider your posting to be a bad joke and hope that it is not
> > intentionnaly just bad taste.
This original hasn't made it to me yet so I don't have all the
context. If this comment by Gerard was aimed at me, then my response
is: I'm assuming that you intended the sym driver to be used for real
applications on real machines. If its only purpose is to run
benchmarks, then let me know that and I will go away.
> I think what you may want to do is ask Kevin to give you some comparisons
> of iostat output from dumps with the ncr driver and dumps with the sym
> driver, ...
I've done a few more tests. I tried to see the effect that the
slow Syquest drive is having. When I dump to an IDE drive then
the sym driver is faster than the ncr by 15-20%. But when I dump
to the Syquest, then the interference slows down the sym driver more
than the ncr. Here's what I got from 8 test runs of dump.
dump from da1 to ad0 (IBM SCSI to WD IDE)
time KB/sec
ncr 246 1764
ncr 250 1736
sym 211 2056
sym 209 2076
dump from da1 to da0 (IBM SCSI to Syjet SCSI)
time KB/sec
ncr 275 1578
ncr 277 1566
sym 335 1295
sym 336 1291
Looking at iostat shows dump pushing 64KB blocks at the Syquest
which is almost keeping up. It gets behind occasionally and
the da1 transfers stop until da0 catches up. With the ncr
driver it looks like this:
tty da0 da1 cpu
tin tout KB/t tps MB/s KB/t tps MB/s us ni sy in id
0 30 64.00 24 1.49 4.75 265 1.23 1 0 5 2 92
0 30 64.00 25 1.55 4.71 219 1.01 1 0 2 1 97
0 30 64.00 23 1.42 0.00 0 0.00 0 0 0 0100
0 30 64.00 25 1.55 0.00 0 0.00 0 0 0 0 99
0 30 53.92 25 1.30 3.56 275 0.96 1 0 6 1 92
0 30 64.00 25 1.55 3.60 564 1.98 0 0 15 2 83
On the sym driver, the pauses from da1 are more frequent and
longer. On the Syquest at da0, there's something strange
going on. The transaction rate on da0 drops way off while it's
trying to catch up, which means that da1 is forced to wait
longer before it can start blasting data at it again.
tty da0 da1 cpu
tin tout KB/t tps MB/s KB/t tps MB/s us ni sy in id
0 30 64.00 22 1.36 2.91 397 1.13 0 0 21 18 60
0 30 64.00 21 1.30 3.41 292 0.97 1 0 14 21 64
0 30 64.00 20 1.24 3.75 82 0.30 0 0 5 21 74
0 30 64.00 21 1.30 0.00 0 0.00 0 0 0 27 72
0 30 64.00 21 1.30 0.00 0 0.00 0 0 0 26 73
0 30 64.00 19 1.18 0.00 0 0.00 0 0 0 24 75
0 89 64.00 17 1.05 0.00 0 0.00 2 0 0 17 81
0 30 64.00 15 0.93 0.00 0 0.00 1 0 0 14 85
0 30 64.00 8 0.50 0.00 0 0.00 0 0 0 8 92
0 30 64.00 8 0.50 0.00 0 0.00 0 0 0 1 99
0 30 55.27 22 1.18 3.69 702 2.53 2 0 11 6 82
0 30 64.00 22 1.36 3.78 670 2.47 1 0 21 16 62
0 30 64.00 23 1.42 3.19 478 1.49 1 0 21 17 61
0 30 64.00 20 1.24 0.00 0 0.00 0 0 0 22 77
0 30 64.00 17 1.05 0.00 0 0.00 1 0 0 16 83
0 30 64.00 8 0.50 0.00 0 0.00 0 0 0 9 91
0 30 64.00 4 0.25 0.00 0 0.00 0 0 0 4 96
0 30 48.95 21 0.99 3.43 520 1.74 2 0 8 2 88
So this would appear to be the cause of the slower dumps.
Perhaps this is error recovery activity on da0? Whatever
it is, the sym driver isn't handling it as gracefully as
the ncr.
--
Kevin Street
street@iname.com
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