On Fri, Jan 04, 2008 at 03:58:31AM -0800, David Miller wrote: > From: Nick Piggin <[EMAIL PROTECTED]> > Date: Fri, 4 Jan 2008 12:33:52 +0100 > > > Just for interest, the lockless pagecache actually makes > > page->_count unstable for all pages that _have ever_ been pagecache > > pages (since the last quiescent rcu state, anyway). Basically, it > > looks up and takes a ref on the struct page without ever having a > > prior pin or reference on that page. It can do this because it knows > > the struct page won't actually get freed. After taking the ref, it > > rechecks that it has got the right page... > > Ok, I understand the needs now. > > I think the way the drivers/net/niu.c driver handles things > would work better. It only performs get_page(), atomic > increments on compound_head(page)->_count, and __free_page(). > Is that all legal with the lockless pagecache?
Yes, you can use the regular refcounting and freeing operations. If the lockless pagecache has got a speculative reference on the page after the driver drops all "real" references, it will take care of freeing the page. > If so I can likely rework the Cassini page management to > behave similarly. If you got the chance, that would be very nice. Thanks, Nick -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
