Messages in this thread | | | From | (Linus Torvalds) | Subject | Re: Buffer and page cache | Date | 8 Nov 1999 17:24:12 GMT |
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In article <000a01bf29a4$ae11ca00$8dbc0280@puffin>, braam <braam@carissimi.coda.cs.cmu.edu> wrote: >-> Yes, bumping the page count is the perfect way to do this. > >If we do that, how can the VM still exert pressure to get rid of dirty >pages?
Right now it can't do that. There's no pressure for VM except for the bdflush deamon, so that's something that you'd have to implement. It shouldn't be that bad - there could easily be some kind of inode-based pressure to throw things out when memory gets tight.
>A "DirtyBit" in the page would give the VM the option of notifying file >systems that have big caches to get rid of pages; now the count is >irrelevant.
The count is still relevant. You should see the count as the main VM way of keeping track of how many owners a page has. You _could_ implement a dirty bit as an additional _hint_, though. A hint for the VM layer to say "Ok, this page is dirty, so I should notify somebody (the inode manager) to try to write things out because we're low on memory".
Linus
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