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Re: Darwin disk I/O question

Hi, Dave,

I'm no expert on this area, but I believe that the "classic" behavior you refer to is *really* classic :-}. With the advent of disk drives with lots of on-board cache, and mini-os's, the host OS has less need to sort disk queues. In fact, it's likely that the host OS gets generic configuration info from the drive, and that the real configuration doesn't match the stated values; if this is the case, anything that the host OS does could be counter-productive.

Regards,

Justin

On Thursday, January 18, 2001, at 08:55 AM, Dave Yost wrote:

> I am seeking a disk driver expert who knows about the following:
>
> I know classically unix has taken the position that disk drivers are expected to keep the
> request queue sorted by cylinder and sector position to minimize total time spent
> waiting for seek and rotational latency, i.e. to maximize total disk throughput.
>
> Is this still true in Darwin? Or do Darwin disk drivers sort requests based on the
> requesting process's priority? Could they if they wanted to, or would there have to be a
> change to the driver protocol?
>
> Thanks
>
> Dave
> _______________________________________________
> darwin-development mailing list
> email@hidden
> http://www.lists.apple.com/mailman/listinfo/darwin-development
>

Justin C. Walker, Curmudgeon-At-Large *
Institute for General Semantics |
Manager, CoreOS Networking | It's not whether you win
Apple Computer, Inc. | or lose...
2 Infinite Loop | It's whether *I* win or lose.
Cupertino, CA 95014 |
*---------------------------------------*-------------------------------*



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