On Tue, 2007-03-06 at 22:24 +0100, Miklos Szeredi wrote: > > I'm not liking this, its not a constant operation as the name implies. > > OK, I'll think of something better. > > > And it style is a bit out of line with the rest of rmap. > > > > The thing it actually does is page_mkclean(), all it doesn't do is > > setting the pte read-only. > > > > I can understand you wanting to avoid the overhead of the minor faults > > resulting from using page_mkclean(), but I'm not sure its worth it. > > It would be nice if the cost of MS_ASYNC wouldn't be too high. And I > do have the feeling that minor faults are far more expensive than > cleaning the dirty bit in the ptes. > > Do you have any numbers? None what so ever, but I always think of msync as a rare function (infrequent when compared to (minor) faults overall). But I don't have numbers backing that up either. Also, the radix tree scan you do isn't exactly cheap either. So what I was wondering is whether its worth optimizing this at the cost of another rmap walker. (one with very dubious semantics at that - it clears the pte dirty bit but doesn't particularly care about that nor does it respect the PG_dirty / PTE dirty relation) - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
