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SubjectRe: mmap() is slower than read() on SCSI/IDE on 2.0 and 2.1
On Fri, Dec 18, 1998 at 09:56:00PM +0100, Rik van Riel wrote:

> - the database stuff you mentioned

doesn't use mmap (well, I don't think it does) <insert raw device
thread here>

> - a lot of tasks that access insanely large 'arrays', eg:
> - (astronomical) image viewers

could be -- arguably, the applications might be able to be coaxed
into reading forwards here

> - matrix solvers

can't comment

> - movie stuff when you watch an image sequence backwards
> (sometimes done during editing, skips because of a faulty
> read-ahead/behind algorithm are not tolerated)

my experience with this was with multi GB files (XFS on SGI vaults,
a couple TB in total) and it bascially came down to raw IO speed, no
kernel trickery here is going to help

smaller streams, maybe

> Why spend money on gobs of disks when you can put a simple
> algorithm in the kernel that accomplishes the same effect?

I aggree with you -- but I'm not convinced having the kernel second
guess the application is a good idea. <insert raw device thread here>




-cw

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