On Mon, 29 Jan 2001, Chris Evans wrote:
> Stephen Tweedie has a rather funky i/o stats enhancement patch which
> should provide what you need. It comes with RedHat7.0 and gives decent
> disk statistics in /proc/partitions.
Monitoring via /proc [not just IO but close to anything] has the
features:
- slow, not atomic, not scalable
- if kernel decides explicitely or due to a "bug" to refuse doing
IO, you get something like this [even using a mlocked, RT monitor],
procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
0 1 1 27116 1048 736 152832 128 1972 2544 869 44 1812 2 43 55
5 0 2 27768 1048 744 153372 52 1308 2668 777 43 1772 2 61 37
0 2 1 28360 1048 752 153900 332 564 2311 955 49 2081 1 68 31
<frozen>
1 7 2 28356 1048 752 153708 3936 0 2175 29091 494 27348 0 1 99
1 0 2 28356 1048 792 153656 172 0 7166 0 144 838 4 17 80
In short, monitoring via /proc is unreliable.
Szaka
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