Subject: Re: slowdown with MI scsi on pmax (ds5000/200)
To: None <tech-kern@netbsd.org, port-pmax@netbsd.org>
From: Toru Nishimura <nisimura@itc.aist-nara.ac.jp>
List: tech-kern
Date: 05/21/2001 17:03:57
Chuck Silvers <chuq@chuq.com> wrote;
> hi,
>
> I went back to run some benchmarks on my decstation 5000/200 again
> first the first time in about a month, and I find that scsi performance
> has dropped considerably.
I'm experiencing similars on my DECstation.
My 1.5V kernel for 33MHz R3000A DECstation brings strange SCSI
performance figures I've never seen before.
NetBSD 1.5V (MAXINE) #0: Tue May 8 13:28:54 JST 2001
nisimura@build:/usr/src/sys/arch/pmax/compile/MAXINE
iozone consistently shows WRITE runs half than READ.
IOZONE performance measurements:
869285 bytes/second for writing the file
2111935 bytes/second for reading the file
The READ performance is restored as good as the one when I made pmax
MI SCSI driver years ago, but WRITE is the worst as long as I know.
iostat and vmstat indicate the kernel beats SCSI hardware par with the
data rate.
$ /usr/sbin/iostat -D 1
KB xfr time
...
854 15 0.52
743 16 0.46
760 18 0.55
786 15 0.48 <------ write has finished here
1311 33 0.63 <------ starts reading
2039 34 0.70
2091 34 0.70
1904 34 0.72
...
$ vmstat 1
procs memory page disk faults cpu
r b w avm fre flt re pi po fr sr s0 in sy cs us sy id
...
1 0 0 20860 1192 0 0 0 215 0 0 15 0 0 0 1 99 0
1 0 0 21708 344 0 0 0 213 0 0 16 0 0 0 0 98 2
1 0 0 21436 616 0 0 0 213 0 0 14 0 0 0 1 99 0
1 0 0 21048 1008 0 0 0 182 0 0 16 0 0 0 1 92 7 <- W
1 0 0 21572 464 0 0 0 213 0 0 38 0 0 0 1 83 16 <- R
1 1 0 21276 780 0 1 0 257 0 0 34 0 0 0 2 91 7
1 0 0 20960 1036 0 2 0 258 0 0 33 0 0 0 3 90 8
1 0 0 20704 1292 0 14 0 393 0 0 32 0 0 0 2 66 32
1 0 0 20768 1232 0 1 0 280 0 0 33 0 0 0 2 92 6
...
The NetBSD/pmax kernel has, UBC, "UBC fix for throttling", SCSIPI
integration and kthread fix.
Tohru Nishimura