From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx206.postini.com [74.125.245.206]) by kanga.kvack.org (Postfix) with SMTP id 0DDE36B0069 for ; Mon, 29 Oct 2012 12:24:33 -0400 (EDT) Date: Mon, 29 Oct 2012 12:23:44 -0400 From: David Teigland Subject: Re: [PATCH v7 10/16] dlm: use new hashtable implementation Message-ID: <20121029162344.GC3516@redhat.com> References: <1351450948-15618-1-git-send-email-levinsasha928@gmail.com> <1351450948-15618-10-git-send-email-levinsasha928@gmail.com> <20121029124655.GD11733@Krystal> <20121029130736.GF11733@Krystal> <20121029160710.GA18944@Krystal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121029160710.GA18944@Krystal> Sender: owner-linux-mm@kvack.org List-ID: To: Mathieu Desnoyers Cc: Sasha Levin , torvalds@linux-foundation.org, tj@kernel.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, paul.gortmaker@windriver.com, davem@davemloft.net, rostedt@goodmis.org, mingo@elte.hu, ebiederm@xmission.com, aarcange@redhat.com, ericvh@gmail.com, netdev@vger.kernel.org, josh@joshtriplett.org, eric.dumazet@gmail.com, axboe@kernel.dk, agk@redhat.com, dm-devel@redhat.com, neilb@suse.de, ccaulfie@redhat.com, Trond.Myklebust@netapp.com, bfields@fieldses.org, fweisbec@gmail.com, jesse@nicira.com, venkat.x.venkatsubra@oracle.com, ejt@redhat.com, snitzer@redhat.com, edumazet@google.com, linux-nfs@vger.kernel.org, dev@openvswitch.org, rds-devel@oss.oracle.com, lw@cn.fujitsu.com On Mon, Oct 29, 2012 at 12:07:10PM -0400, Mathieu Desnoyers wrote: > I'm fine with turning a direct + modulo mapping into a dispersed hash as > long as there are no underlying assumptions about sequentiality of value > accesses. > > If the access pattern would happen to be typically sequential, then > adding dispersion could hurt performances significantly, turning a > frequent L1 access into a L2 access for instance. > All I'm asking is: have you made sure that this hash table is not > deliberately kept sequential (without dispersion) to accelerate specific > access patterns ? This should at least be documented in the changelog. It was not intentional. I don't expect any benefit would be lost by making it non-sequential. -- 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