Messages in this thread | | | Date | Wed, 9 Jul 2008 01:20:31 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH 3/3] Add timeout feature |
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On Wed 2008-07-09 09:10:27, Dave Chinner wrote: > On Mon, Jul 07, 2008 at 01:07:31PM +0200, Pavel Machek wrote: > > Hi! > > > > > I still disagree with this whole patch. There is not reason to let > > > the freeze request timeout - an auto-unfreezing will only confuse the > > > hell out of the caller. The only reason where the current XFS freeze > > > call can hang and this would be theoretically useful is when the > > > > What happens when someone dirties so much data that vm swaps out > > whatever process that frozen the filesystem? > > a) you can't dirty a frozen filesystem - by definition a frozen > filesystem is a *clean filesystem* and *cannot be dirtied*.
Can you stop me?
mmap("/some/huge_file", MAP_SHARED);
then write to memory mapping?
> b) Swap doesn't write through the filesystem > c) you can still read from a frozen filesystem to page your > executable?? in.
atime modification should mean dirty data, right? And dirty data mean memory pressure, right?
> d) if dirtying another unfrozen filesystem swaps out your ~~~~~~~ > application so it can't run, then there's a major VM bug. > Regardless, until the app completes it is relying on the > filesystem being frozen, so it better remain frozen....
Agreed. With emphasis on "another".
> > I though that was why the timeout was there... > > Not that I know of.
Ok, lets see how you deal with mmap. Pavel
-- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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