Subject: Re: sd rereads
To: None <>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: tech-kern
Date: 09/01/1999 22:52:49
>>> How about this for a compromise: on re-open, we check to see if the
>>> diskabel block has changed and only recompute the in-core disklabel
>>> if it's changed.
>> I think this is an excellent suggestion.  It seems to me that it
>> addresses all the problems I've heard raised: [...]
> It seems to me that this general notion is better accomplished
> (without waste of memory or need for a checksum) by what I suggested.

Just to make sure we're talking about the same thing, you are referring
to making DIOCSDINFO set the in-core label sticky, DIOCWDINFO set it
non-sticky, and then have sticky (but only sticky) in-core labels
persist across all-partitions-closed, right?  And not even sticky
labels persist across media change, for removable drives?

In that case, I see a price to it: it seems to me - and to you too,
based on the message I saw - that it calls for at least one new ioctl,
to de-sticky a sticky in-core label.

Personally, I prefer to "waste" memory on storing the label sector than
to "waste" the resources that would be consumed by your approach
(mostly the extra ioctl) - and unless there are spare bits lying around
already, adding a sticky bit will grow the structure just as much as
adding a checksum.  (I put "waste" in quotes both times because, as
seems obvious from the conversation, not everyone agrees on which ones
are actually "waste", as opposed to "worthwhile investment".)

					der Mouse

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