Re: CSCAN I/O scheduler for 2.6.10 kernel

[Bill Davidsen <davidsen@tmr.com>]

Vishal Patil wrote:
> Maintain two queues which will be sorted in ascending order using Red
> Black Trees. When a disk request arrives and if the block number it
> refers to is greater than the block number of the current request
> being served add (merge) it to the first sorted queue or else add
> (merge) it to the second sorted queue. Keep on servicing the requests
> from the first request queue until it is empty after which switch over
> to the second queue and now reverse the roles of the two queues.
> Simple and Sweet. Many thanks for the awesome block I/O layer in the
> 2.6 kernel.
> 
Why both queues sorting in ascending order? I would think that one 
should be in descending order, which would reduce the seek distance 
between the last i/o on one queue and the first on the next.

-- 
    -bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
  last possible moment - but no longer"  -me