On 22 Dec 2008 at 5:11, Eric wrote:

> Besides that, I don't think I totally agree on your statement. Letting
> the IO scheduler taking the actual disk geometry into account, should
> give more performance. However, the fdisk default values are probably
> standard for disks these days.

The disk scheduler can safely assume that contiguous nearby "forward" requests 
perform better than small scattered "backwards" requests. All other is mostly 
speculative IMHO. You would have to know about the heads position relative in 
time, track skew, sector skew, etc. Today's disk have cache big enough for 
tracks, so the scheduler shouldn't really care about sectors. Also the 
really cannot know on which physical cylinder (or track, or head) a specific 
will actually reside.

However when we are talking about problems in the scheduler _software_ you may 
right. I didn't look into it for years ;-)


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