Messages in this thread | | | Date | Mon, 21 Jan 2002 00:30:43 +0300 | From | Hans Reiser <> | Subject | Re: Possible Idea with filesystem buffering. |
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Rik van Riel wrote:
>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. > So basically you continue to believe that one cache manager shall rule them all, and in the darkness as to their needs, bind them.
> > >>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. > Care to explain more?
> > >regards, > >Rik >
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