On Sat, 16 Feb 2008, Phoenix Kiula wrote:

The script you suggested doesn't work:
   tmp > ./trackusage.sh
   -bash: ./trackusage.sh: /bin/sh: bad interpreter: Permission denied

Try changing the first line to

#!/bin/bash

Anyway, I did the vmstat command. I was running it while the system
was ok, then not ok, then ok...and so on. So I hope these numbers have
captured what the issue is:

tmp > vmstat 10 60
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
0  0   3380 323140 115248 2995560    0    0     0    60 1097   153  1  0 97  2
0  0   3380 280260 115272 2995536    0    0     0    77 1087   133  1  0 98  1
0  0   3380 200580 115296 2995512    0    0     2    65 1089   140  1  0 97  2
0  0   3380  81916 115392 2995676    0    0    17    82 1089   188  2  1 94  2
0  0   3380  16980  98072 2974256    0    0    48   122 1102   190  2  1 95  3
1  0   3380  21588  73160 2954708    0    0    86   274 1128   276  2  2 88  8
0  0   3380  52692  57860 2932048    0    0     1   128 1106   211  2  1 95  3
0  0   3380 184748  57960 2931948    0    0     6   219 1128   451  2  1 92  5
0  0   3380 342996  58016 2931892    0    0     0   140 1122   465  2  1 94  3

Looks like the worst spot was in the middle here. Something gobbled up over 300MB of memory in 40 seconds, enough to force the OS to blow away almost half its disk buffers just to keep working memory free. Not so bad that it went to swap or invoked the OOM killer but enough to push the I/O block out (bo) up. I would guess the other ugly spots were the later portions where the bo spiked >100.

But without knowing more about what the processing using this memory and generating the output I/O are doing it's hard to say why. That's why I suggested you watch top with the command lines turned on for a bit, to see what process(es) are jumping around during the bad periods.

--
* Greg Smith [EMAIL PROTECTED] http://www.gregsmith.com Baltimore, MD

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