Re: detecting hard disk idleness

Richard B. Johnson (root@chaos.analogic.com)
Wed, 21 Aug 2002 15:07:00 -0400 (EDT)


On Wed, 21 Aug 2002, Mukesh Rajan wrote:

> this again would mean that i would have to poll the /proc/interrupt file.
> i want to avoid polling because of very small poll interval causing
> overhead. i am still wondering if this could be implemented with some sort
> of interrupt mechanism in linux (kernel interrupting user program or user
> program waiting on some signal)
>
> - mukesh
>

Hard disk 'idleness' is something you would check at a 1-second
interval. As such, its overhead is very small.

This is a sample at 1 second intervals during a kernel compile:

11: 4667 4585 IO-APIC-level BusLogic BT-958
11: 4667 4585 IO-APIC-level BusLogic BT-958
11: 4667 4585 IO-APIC-level BusLogic BT-958
11: 4667 4585 IO-APIC-level BusLogic BT-958
11: 4667 4585 IO-APIC-level BusLogic BT-958
11: 4667 4585 IO-APIC-level BusLogic BT-958
11: 4667 4585 IO-APIC-level BusLogic BT-958
11: 4667 4585 IO-APIC-level BusLogic BT-958
11: 4670 4588 IO-APIC-level BusLogic BT-958
11: 4670 4588 IO-APIC-level BusLogic BT-958
11: 4670 4588 IO-APIC-level BusLogic BT-958
11: 4670 4588 IO-APIC-level BusLogic BT-958
11: 4670 4588 IO-APIC-level BusLogic BT-958
11: 4670 4588 IO-APIC-level BusLogic BT-958
11: 4670 4588 IO-APIC-level BusLogic BT-958
11: 4670 4588 IO-APIC-level BusLogic BT-958

Cheers,
Dick Johnson
Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).
The US military has given us many words, FUBAR, SNAFU, now ENRON.
Yes, top management were graduates of West Point and Annapolis.

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