From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Graf Subject: Re: [v3 PATCH 9/9] rhashtable: Add immediate rehash during insertion Date: Mon, 23 Mar 2015 21:56:32 +0000 Message-ID: <20150323215632.GA22099@casper.infradead.org> References: <20150323134955.GA16328@gondor.apana.org.au> <20150323165033.GD20752@casper.infradead.org> <20150323214422.GA19938@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "David S. Miller" , Eric Dumazet , Patrick McHardy , Josh Triplett , "Paul E. McKenney" , netdev@vger.kernel.org To: Herbert Xu Return-path: Received: from casper.infradead.org ([85.118.1.10]:59283 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752214AbbCWV4e (ORCPT ); Mon, 23 Mar 2015 17:56:34 -0400 Content-Disposition: inline In-Reply-To: <20150323214422.GA19938@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: On 03/24/15 at 08:44am, Herbert Xu wrote: > I specifically made it this way because I don't think the users > should be touching the actual limit. This is something that you > always want to enable unless you're in the situation of netfilter > where you don't care. > > If you did care then 16 is sort of intrinsic to the 32-bit hash > that we're using. Going below doesn't make much sense because > you may run into false warnings due to double rehashes (that's > how I discovered 4 was uesless, very quickly :) Remember the > rehash is only there to detect pathological cases where people > are actively attacking us. Otherwise the 100% utilisation check > will kick in. > > Going above 16 means that you're hashing multiple objects with > the same key. Then you'd want to disable this altogether. > > The rhashtable already has too many knobs and I don't want to > add anything unnecessary to rhashtable_params. OK. I can certinaly live with this. You are certinaly right that simplicity isn't a bad move here. Thanks for being patience and answering all the questions. Acked-by: Thomas Graf