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Re: CVS commit: src/sys

On Mon, Feb 23, 2009 at 09:23:56PM +0000, Andrew Doran wrote:
> I didn't phrase that very well. I mean if you only read a file but never
> dirty it, the atime update won't go out until unmount. Since writing the
> original mail I learned that sync() won't even push it. This is now fixed.
> The same issue also affected device nodes.

This was deliberate; at the time it was a way to avoid spinning up
disks on laptops, just for atime updates. 

The fact that sync didn't push them either was an unfortunate
implementation issue.

Yes, there should be A Better Way, allowing writes to be prioritised
and classified such that they can trickle out while the disk is
spinning, but not cause it to spin up until a higher-priority IO
request comes.  We have the beginnings of this now, but the fs
consequences of holding those writes at the disk layer are unclear.


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