Messages in this thread |  | | From | Daniel Phillips <> | Subject | Re: Getting FS access events | Date | Tue, 15 May 2001 12:33:35 +0200 |
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On Tuesday 15 May 2001 08:57, Alexander Viro wrote: > On Tue, 15 May 2001, Richard Gooch wrote: > > > What happens if you create a buffer cache entry? Does that > > > invalidate the page cache one? Or do you just allow invalidates > > > one way, and not the other? And why= > > > > I just figured on one way invalidates, because that seems cheap and > > easy and has some benefits. Invalidating the other way is costly, > > so don't bother, even if there were some benefits. > > Cute. > * create an instance in pagecache > * start reading into buffer cache (doesn't invalidate, right?) > * start writing using pagecache > * lose the page > * try to read it (via pagecache) > Woops - just found a copy in buffer cache, let's pick data from it. > Pity that said data is obsolete...
That's because you left out his invalidate:
* create an instance in pagecache * start reading into buffer cache (doesn't invalidate, right?) * start writing using pagecache (invalidate buffer copy) * lose the page * try to read it (via pagecache)
Everthing ok. As an optimization, instead of 'lose the page', do 'move page blocks to buffer cache'.
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