On Wed, 24 Apr 2002, mlw wrote: > I am not arguing about whether or not they do it, I am saying it is > not always possible. I/O requests do not remain in queue waiting for > reordering indefinitely.
It doesn't matter. When they go out to the disk they go out in order. On every Unix-based OS I know of, and Novell Netware, if you submit a single read request for consecutive blocks, those blocks *will* be read sequentially, no matter what the system load. So to get back to the original arugment: > > >The supposed advantage of a sequential read over an random read, in > > >an active multitasking system, is a myth. If you are executing one > > >query and the system is doing only that query, you may be right. No, it's very real, because your sequential read will not be broken up. If you think it will, let me know which operating systems this happens on, and how exactly it happens. cjs -- Curt Sampson <[EMAIL PROTECTED]> +81 90 7737 2974 http://www.netbsd.org Don't you know, in this new Dark Age, we're all light. --XTC ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
