From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 7 Oct 2008 09:53:09 +0200 From: Nick Piggin Subject: Re: [patch][rfc] ddds: "dynamic dynamic data structure" algorithm, for adaptive dcache hash table sizing (resend) Message-ID: <20081007075309.GA16143@wotan.suse.de> References: <20081007064834.GA5959@wotan.suse.de> <20081007070225.GB5959@wotan.suse.de> <20081007071827.GB5010@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081007071827.GB5010@infradead.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Hellwig Cc: Linux Kernel Mailing List , Linux Memory Management List , netdev@vger.kernel.org, Paul McKenney List-ID: On Tue, Oct 07, 2008 at 03:18:27AM -0400, Christoph Hellwig wrote: > > > > I'm cc'ing netdev because Dave did express some interest in using this for > > some networking hashes, and network guys in general are pretty cluey when it > > comes to hashes and such ;) > > Without even looking at the code I'd say geeting the dcache lookup data > structure as a hash is the main problem here. Dcache lookup is > fundamentally a tree lookup, with some very nice domain splits > (superblocks or directories). Dcache lookup is partially a tree lookup, but also how do you look up entries in a given directory? That is not naturally a tree lookup. Could be a per directory tree, though, or a hash, or trie. Anyway, I don't volunteer to change that just yet ;) > Mapping these back to a global hash is > a rather bad idea, not just for scalability purposes. I don't disagree. But it can be improved by dynamically resizing until it is replaced. I guess it is also a demonstration of how to implement the algorithm. PID hash is probably another good one to convert. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org