Messages in this thread | | | Date | Sun, 20 Jan 2002 19:24:57 -0200 (BRST) | From | Rik van Riel <> | Subject | Re: Possible Idea with filesystem buffering. |
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On Mon, 21 Jan 2002, Hans Reiser wrote: > Rik van Riel wrote: > >On Sun, 20 Jan 2002, Hans Reiser wrote:
> >Agreed on these points, but you really HAVE TO work towards > >flushing the page ->writepage() gets called for. > > > >Think about your typical PC, with memory in ZONE_DMA, > >ZONE_NORMAL and ZONE_HIGHMEM. If we are short on DMA pages > >we will end up calling ->writepage() on a DMA page. > > > >If the filesystem ends up writing completely unrelated pages > >and marking the DMA page in question referenced the VM will > >go in a loop until the filesystem finally gets around to > >making a page in the (small) DMA zone freeable ... > > This is a bug in VM design, yes? It should signal that it needs the > particular page written, which probnably means that it should use > writepage only when it needs that particular page written,
That is exactly what the VM does.
> and should otherwise check to see if the filesystem supports something > like pressure_fs_cache(), yes?
That's incompatible with the concept of memory zones.
regards,
Rik -- "Linux holds advantages over the single-vendor commercial OS" -- Microsoft's "Competing with Linux" document
http://www.surriel.com/ http://distro.conectiva.com/
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