Re: (reiserfs) Re: More on 2.2.18pre2aa2 (summary of elevator ideas)

From: Andrew Scott (A.J.Scott@casdn.neu.edu)
Date: Wed Sep 13 2000 - 14:02:59 EST


On 12 Sep 2000, at 18:08, Ed Tomlinson wrote:

> Hi,
>
> I made the comment because I remember back when the discussion was current
> on linux kernel. I thought Jeff Merkey's, message was to the point. Para-
> phrasing from memory, it was something to the effect that novell had
> tried many elevators. All had problems with some loads. The best they
> had found was the 'close the door' idea. I do not remember if the door
> was based on requests or time. Another point to remember is that the
> netware people came up with a what they considered a good solution.

I believe that the Netware elevator is based on outstanding requests.
This is a tunable parameter which may be increased for fast disk
subsystems.

I think that you could consider the number of requests to be loosely
related to time. That is, the time to service 50 requests should be
fairly predictable for a given disk/controller. I don't think you
need to time stamp every request to get good results.

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