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SubjectRe: High load average on disk I/O on 2.6.17-rc3
Date
Hi Bert,

That's interesting, I didn't know that about the vmstat command, I will
definitely use that more in the future. I went ahead and did an ncftpget and
started vmstat 1 at the same time, I've attached the output here. It looks
like the 'id' column was at 100, and then as soon as I started ncftpget, it
went down to 0 the whole time.

The interesting thing was that after I did a Ctrl-C on the ncftpget, the id
column was still at 0, even though the ncftpget process was over. The id
column was at 0 and the 'wa' column was at 98, up until all of the pdflush
processes ended.

Is that the expected behavior?

Jason

-------Original Message-----
From: bert hubert
Sent: Saturday 06 May 2006 16:03
To: Jason Schoonover
Subject: Re: High load average on disk I/O on 2.6.17-rc3
On Fri, May 05, 2006 at 10:10:19AM -0700, Jason Schoonover wrote:
> Whenever I copy any large file (over 500GB) the load average starts to
> slowly rise and after about a minute it is up to 7.5 and keeps on rising
> (depending on how long the file takes to copy). When I watch top, the
> processes at the top of the list are cp, pdflush, kjournald and kswapd.

Load average is a bit of an odd metric in this case, try looking at the
output from 'vmstat 1', and especially the 'id' column. As long as that
doesn't rise, you don't have an actual problem.

The number of processes in the runqueue doesn't really tell you anything
about how much CPU you are using.

Having said that, I think there might be a problem to be solved.

Bert
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
0 0 40 1991860 9444 14900 0 0 57 136 148 8 0 0 98 1
0 0 40 1991860 9452 14892 0 0 0 372 1048 24 0 0 100 0
0 0 40 1991860 9464 14880 0 0 4 36 1051 75 0 0 100 1
0 0 40 1991860 9464 14880 0 0 0 0 1032 52 0 0 100 0
0 0 40 1991860 9464 14880 0 0 0 0 1033 42 0 0 100 0
1 0 40 1971532 9536 35480 0 0 236 0 4944 401 1 10 87 4
1 0 40 1891056 9620 114616 0 0 4 176 17382 276 1 35 65 0
1 1 40 1805372 9712 198232 0 0 4 48784 18660 285 1 38 52 9
1 3 40 1723160 9792 279208 0 0 0 70868 18481 318 1 39 19 43
0 4 40 1704684 9812 297344 0 0 4 16480 4864 127 0 8 0 92
1 3 40 1657068 9860 344148 0 0 0 18040 10767 245 0 21 0 78
0 2 40 1581072 9940 420636 0 0 0 2436 16886 332 1 40 17 43
1 4 40 1521800 10000 477152 0 0 4 34660 12934 306 0 30 12 58
1 4 40 1441696 10076 554936 0 0 0 26912 17277 338 0 35 0 64
0 4 40 1399660 10120 595760 0 0 4 31944 9725 251 0 19 0 81
1 4 40 1326128 10192 667292 0 0 0 34668 15984 339 1 33 0 67
1 4 40 1273056 10244 718648 0 0 4 35376 11855 266 0 24 0 76
1 4 40 1190968 10324 798468 0 0 0 10228 17557 357 1 35 5 59
1 4 40 1112724 10396 874624 0 0 0 27844 16982 376 1 34 5 61
0 5 40 1044168 10468 941668 0 0 4 32492 15184 346 0 30 2 67
1 4 40 997668 10512 986912 0 0 0 22632 10538 244 1 22 0 78
0 4 40 926120 10576 1056344 0 0 0 13724 15436 332 1 34 0 65
1 5 40 889656 10628 1094712 0 0 4 28000 9218 285 0 22 5 74
0 6 40 859028 10660 1124600 0 0 0 13768 7295 196 0 15 0 84
0 7 40 833856 10684 1148852 0 0 0 12324 6169 165 0 12 0 88
Did a Ctrl-C here

0 2 40 47312 7888 1920116 0 0 0 36452 1353 52 0 2 39 60
0 2 40 47816 7888 1920116 0 0 0 36264 1354 56 0 1 0 99
0 2 40 48312 7888 1920116 0 0 0 36248 1362 52 0 1 0 99
0 2 40 48808 7888 1920116 0 0 0 36040 1362 56 0 1 0 99
0 2 40 49180 7888 1920116 0 0 0 36592 1360 54 0 2 0 99
0 2 40 49552 7888 1920116 0 0 0 36064 1355 56 0 2 0 98
0 2 40 50048 7888 1920116 0 0 0 36576 1360 54 0 2 0 99
0 2 40 50544 7888 1920116 0 0 0 36340 1351 57 0 1 0 99
0 2 40 51040 7888 1920116 0 0 0 36164 1352 51 0 2 0 99
0 2 40 51412 7888 1920116 0 0 0 36044 1367 57 0 1 0 99
0 2 40 51908 7888 1920116 0 0 0 36204 1359 51 0 1 0 99
0 2 40 52404 7888 1920116 0 0 0 36012 1363 55 0 2 0 99
0 2 40 52776 7888 1920116 0 0 0 36280 1362 68 0 1 0 99
0 2 40 53140 7888 1920116 0 0 0 36236 1395 251 0 2 0 98
0 2 40 53760 7888 1920116 0 0 0 36316 1359 53 0 2 0 99
0 2 40 54504 7888 1920116 0 0 0 36468 1356 55 0 2 0 98
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