Messages in this thread | | | Date | Wed, 5 Jun 2002 13:22:55 +0200 | From | Pavel Machek <> | Subject | Re: [patch 5/18] mark swapout pages PageWriteback() |
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Hi!
> > > In short the same way MAP_ANON must pageout correctly, also MAP_SHARED > > > must swapout correctly with very vm intensive conditions. > > I strongly agree with Andrea on that. Swap fault without page lock > was a step forward, reinstating it in the light of observed degradation > in one workload was right decision for that particular tail of release, > but it's a shame to have stayed that way. > > > That is true, but it is ignoring the fact that there _are_ real technical > > differences between swap cache mappings and regular shared mappings. > > > > One major difference is the approach to the last user: a last use of a > > shared mapping still needs to write out dirty state, while the last use of > > a swap page is better off noticing that it should just optimize away the > > write, and we can just turn the page back into a dirty anonymous page. > > Poor example: isn't last use of swap page just like last use of > shared mapping of an _unlinked_ file?
Eh? Suppose I have two different shared mappings of (unlinked:3). It may be last use of swap page in first mapping, but what prevents me from seeking and trying to read what I wrote? Pavel
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