From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 8 Oct 2008 05:27:15 +0200 From: Nick Piggin Subject: Re: [patch][rfc] ddds: "dynamic dynamic data structure" algorithm, for adaptive dcache hash table sizing Message-ID: <20081008032714.GD6499@wotan.suse.de> References: <20081007064834.GA5959@wotan.suse.de> <20081007.140825.40261432.davem@davemloft.net> <20081008024813.GC6499@wotan.suse.de> <20081008031245.GC7101@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081008031245.GC7101@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org Return-Path: To: "Paul E. McKenney" Cc: David Miller , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-netdev@vger.kernel.org, josh@freedesktop.org List-ID: On Tue, Oct 07, 2008 at 08:12:45PM -0700, Paul E. McKenney wrote: > On Wed, Oct 08, 2008 at 04:48:13AM +0200, Nick Piggin wrote: > > On Tue, Oct 07, 2008 at 02:08:25PM -0700, David Miller wrote: > > > From: Nick Piggin > > > Date: Tue, 7 Oct 2008 08:48:34 +0200 > > > > > > > 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 ;) > > > > > > Interesting stuff. > > > > > > Paul, many months ago, forwarded to me a some work done by Josh > > > Triplett called "rcuhashbash" which had similar objectives. He did > > > post it to linux-kernel, and perhaps even your ideas are inspired by > > > his work, I don't know. :-) > > > > Hmm yes I did see that. It's not too similar, as it focuses on re-keying > > an existing element into the same hash table. ddds can't do that kind of > > thing (the underlying data structure isn't visible to the algorithm, so > > it can't exactly modify data structures in-place), although in another > > sense it is more general because the transfer function could transfer > > items into another hash table and re-key them as it goes (if it did that, > > it could probably use Josh's "atomic" re-keying algorithm too). > > > > But largely it does seem like they are orthogonal (if I'm reading > > rcuhashbash correctly). > > IIRC, one of the weaknesses of rcuhashbash was that the elements had > to be copied in some cases. Yes, I noticed that. > Josh has been working on a variant that > (hopefully) allows elements to be moved without copying, as is required > by dcache. So is it able to actually resize the hash table? If so, I couldn't quite see how it works; if not, I'd be interested to know what is the application to dcache. Josh? Thanks, Nick -- 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