slow i/o

From: Fu-Ming Tao <ftao_at_jell.fullerton.edu>
Date: Sun, 3 Mar 1996 20:05:40 -0800 (PST)

Hi,

We have an alpha 600 5/266 (128 MB) that we run Gaussian94 on. We have
noticed rather low cpu usage (~20%), possibly due to low i/o. We tried to
improve performance by changing ubc_maxpercent from 100 to 40, to no
avail. Below is some output. Maybe it's helpful... Any tips would be
greatly appreciated, and if it's RTFM, please include the title :-)

Thanks for your help,
Fu-Ming

# vmstat

Virtual Memory Statistics: (pagesize = 8192)
  procs memory pages intr cpu
  r w u act free wire fault cow zero react pin pout in sy cs us
sy id
  2 50 13 9798 3603 1672 386K 74K 78K 170 50K 0 57 98 360 45
6 50

# iostat

      tty rz0 rz1 rz5 fd0 cpu
 tin tout bps tps bps tps bps tps bps tps us ni sy id
   0 7 89 5 2299 44 0 0 0 0 45 0 6 50

# swapon -s

Swap partition /dev/rz0b (default swap):
    Allocated space: 48801 pages (381MB)
    In-use space: 5893 pages ( 12%)
    Free space: 42908 pages ( 87%)


Total swap allocation:
    Allocated space: 48801 pages (381MB)
    Reserved space: 7913 pages ( 16%)
    In-use space: 5893 pages ( 12%)
    Available space: 40888 pages ( 83%)

# ps aux | more

USER PID %CPU %MEM VSZ RSS TTY S STARTED TIME
COMMAND
ftao 551 9.0 25.5 49.3M 323 ?? U 19:22:35 06:44:44
/data/g9
ftao 5034 0.0 0.3 1.87M 328K ttyp1 S 08:30:21 0:00.76 -
(csh)
root 5033 0.0 0.9 7.99M 1.1M ?? S 08:30:20 0:02.08
/usr/bin
root 0 0.0 4.4 129M 5.5M ?? R < 19:08:35 2:16.31
[kernel
root 5126 0.0 0.2 1.45M 208K ttyp1 R + 09:06:23 0:00.02 ps
aux
ftao 5136 0.0 0.1 1.23M 112K ttyp1 S + 09:06:23 0:00.01 head
root 456 0.0 2.4 11.3M 3.0M ?? S < 19:09:31 1:44.78
/usr/bin
root 18 0.0 0.0 184K 24K ?? S 19:09:05 0:13.02
/sbin/up
root 1 0.0 0.0 304K 48K ?? I 19:08:35 0:00.80
/sbin/in
Received on Tue Mar 05 1996 - 05:20:45 NZDT

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