Re: strange idle%

Riley Williams (rhw@MemAlpha.CX)
Tue, 11 May 1999 18:49:28 +0100 (GMT)


Hi there.

> I was running top, and I noticed a very odd idle% pop up from
> time to time:

> 11:03am up 11:04, 1 user, load average: 2.00, 2.00, 2.00
> 36 processes: 32 sleeping, 4 running, 0 zombie, 0 stopped
> CPU states: 0.4% user, 0.1% system, 99.4% nice, 428639.3% idle
> ^^^^^^^^^

> I'm running the rc5des client on both cpu's of my dual PII
> running 2.2.7. Nothing bad has happened, but I'm curious as to
> whether this might be an overflow in whatever file in /proc top
> get's its info from...

Looks like some form of underflow to me...

Note that ( (2^32 -1) / 100 ) / 100 = 429,496.7295 and that's not much
larger than the value quoted...

Before anybody asks, take a 32-bit unsigned field and put -1 in it,
and you get 2^32-1 which you then divide by HZ=100 and then by 100 to
get percent...

Best wishes from Riley.

+----------------------------------------------------------------------+
| There is something frustrating about the quality and speed of Linux |
| development, ie., the quality is too high and the speed is too high, |
| in other words, I can implement this XXXX feature, but I bet someone |
| else has already done so and is just about to release their patch. |
+----------------------------------------------------------------------+
* ftp://ftp.MemAlpha.cx/pub/rhw/Linux
* http://www.MemAlpha.cx/kernel.versions.html

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