Date: Mon, 27 Mar 2000 18:01:56 -0600 (CST) From: Matthew Hanselman <mjhans@cs.wisc.edu> To: ken@kdm.org Cc: freebsd-scsi@FreeBSD.ORG Subject: Re: Terrible SCSI performance with 4.0 -- please help Message-ID: <Pine.GSO.3.96L.1000327175323.15434A-100000@alumni.cs.wisc.edu>
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Before I get into the my message, thanks for the help!
Here's my info:
No errors, at least in /var/log/messages. Just the expected (?) diag re:
the controllers/disks upon boot, which mimics that of dmesg:
da0 at ahc0 bus 0 target 0 lun 0
da0: <IBM DMVS18V 0250> Fixed Direct Access SCSI-3 device
da0: 80.000MB/s transfers (40.000MHz, offset 31, 16bit), Tagged Queueing Enabled
da0: 17501MB (35843670 512 byte sectors: 255H 63S/T 2231C)
(Same for da1, 2, and 3)
Here's the IDE disk, FYI:
ad0: 6149MB <QUANTUM FIREBALL CX6.4A> [13328/15/63] at ata0-master using UDMA33
As for caching, I don't know how to make out all of these options, but
here's your requested info from camcontrol:
IC: 0
ABPF: 0
CAP: 0
DISC: 0
SIZE: 0
WCE: 0
MF: 0
RCD: 0
Demand Retention Priority: 1
Write Retention Priority: 1
Disable Pre-fetch Transfer Length: 65535
Minimum Pre-fetch: 0
Maximum Pre-fetch: 65535
Maximum Pre-fetch Ceiling: 65535
Getting into benchmarking: Funny thing is bonnie makes it look as though
the drives are similar. Here was my original benchmark that confirms disk
times: copying a tar file of size 26M to a directory and untarring it into
the same directory, doing so a couple of times to take caching into
account. Here's the output time from that:
For the IDE disk:
% time tar xf apache.tar
0.071u 1.559s 0:05.62 28.8% 318+308k 2+1996io 0pf+0w
For the SCSI disk:
% time tar xf apache.tar
0.095u 1.396s 0:10.11 14.6% 313+303k 2+2166io 0pf+0w
Here's bonnie output for the IDE disk:
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
60 13247 97.2 18640 51.0 23199 75.2 16173 99.9 95878 100.0 11389.4 97.4
This seems to be taking about about 50% user and about 40% system time
For the SCSI disk:
-------Sequential Output-------- ---Sequential Input-- --Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
60 12845 96.6 27812 73.4 30856 93.6 15726 99.6 96393 98.8 11477.9 99.8
This seems to be taking about 60% user and about 30% system time...
Finally, iozone for the IDE disk:
random random
KB reclen write rewrite read reread read write
60000 4 14156 17189 61853 72246 52582 831
bkwd record stride
read rewrite read fwrite frewrite fread freread
50540 120910 62517 14640 17569 49850 60480
And for the SCSI disk (Note the write being 95% bigger, etc):
random random
KB reclen write rewrite read reread read write
60000 4 27227 28223 86392 65592 67151 1213
bkwd record stride
read rewrite read fwrite frewrite fread freread
88551 115087 67553 21548 18198 51120 75003
top said the CPU was mostly idle (around 80-90% idle) during these...
Any ideas?
- Matt
> Well, it'll take a little more information to try to track down the
> problem.
>
> How about dmesg output, and benchmark numbers from bonnie and iozone.
>
> Also, is write caching enabled or disabled on those drives? You can find
> out with camcontrol, like this:
>
> camcontrol modepage da0 -m 8
>
> will print out mode page 8 for da0.
>
> While you're doing the benchmarks, run top(1) to see if you're CPU bound.
>
> Also, are you getting any error messages?
>
> Ken
> --
> Kenneth Merry
> ken@kdm.org
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