Subject: Re: Disk scheduling policy (Re: NEW_BUFQ_STRATEGY)
To: None <tech-kern@NetBSD.org, tech-perform@NetBSD.org>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
Date: 12/01/2003 19:56:18
>> Really, it's not clear that the elevator sort buys you much anyway,
>> when you're talking to raw disks, because disks don't really expose
>> their real geometry anymore.
> Well, I have yet to encounter one that randomly shuffles blocks such
> that sorting in order of increasing block number would be _harmful_.
Not randomly, maybe, but unless you can get the disk to tell you about
every damaged block it's reassigned, and where it's been reassigned to,
you can't know whether you're sending requests in physical order.
(Whether this is a big enough effect to matter is another question, one
for experiment rather than theory.)
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