From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760175AbYDNIdu (ORCPT ); Mon, 14 Apr 2008 04:33:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756082AbYDNIdm (ORCPT ); Mon, 14 Apr 2008 04:33:42 -0400 Received: from ecfrec.frec.bull.fr ([129.183.4.8]:47479 "EHLO ecfrec.frec.bull.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755737AbYDNIdl (ORCPT ); Mon, 14 Apr 2008 04:33:41 -0400 Message-ID: <480316D3.7070901@bull.net> Date: Mon, 14 Apr 2008 10:33:23 +0200 From: Nadia Derbey Organization: BULL/DT/OSwR&D/Linux User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040115 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Peter Zijlstra Cc: efault@gmx.de, manfred@colorfullife.com, linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, akpm@linux-foundation.org, xemul@openvz.org Subject: Re: [PATCH 00/13] Re: Scalability requirements for sysv ipc References: <20080411161702.460410000@bull.net> <1207931235.7157.0.camel@twins> <4802E93E.4090205@bull.net> <1208157359.7427.25.camel@twins> In-Reply-To: <1208157359.7427.25.camel@twins> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra wrote: > On Mon, 2008-04-14 at 07:18 +0200, Nadia Derbey wrote: > >>Peter Zijlstra wrote: >> >>>On Fri, 2008-04-11 at 18:17 +0200, Nadia.Derbey@bull.net wrote: >>> >>> >>>>Here is finally the ipc ridr-based implementation I was talking about last >>>>week (see http://lkml.org/lkml/2008/4/4/208). >>>>I couldn't avoid much of the code duplication, but at least made things >>>>incremental. >>>> >>>>Does somebody now a test suite that exists for the idr API, that I could >>>>run on this new api? >>>> >>>>Mike, can you try to run it on your victim: I had such a hard time building >>>>this patch, that I couldn't re-run the test on my 8-core with this new >>>>version. So the last results I have are for 2.6.25-rc3-mm1. >>>> >>>>Also, I think a careful review should be done to avoid introducing yet other >>>>problems :-( >>> >>> >>>Why duplicate the whole thing, when we converted the Radix tree to be >>>RCU safe we did it in-place. Is there a reason this is not done for idr? >>> >>> >>> >> >>I did that because I wanted to go fast and try to fix the performance >>problem we have with sysV ipc's. I didn't want to introduce (yet other) >>regressions in the code that uses idr's today and that works well ;-) >>May be in the future if this rcu based api appears to be ok, we can >>replace one with the other? > > >>>From what I can see the API doesn't change at all, Well, 1 interface changes, 1 is added and another one went away: 1) for the preload part (it becomes like the radix-tree preload part): int idr_pre_get(struct idr *, gfp_t); would become int idr_pre_get(gfp_t); 2) idr_pre_get_end() is added (same as radix_tree_preload_end()). 3) The idr_init() disappears. You might see that other interfaces are not provided by ridr, but this is only because I've taken those that are useful for the ipc part (so should not be a problem to make the whole thing rcu safe). > so I don't see why > you need to duplicate - either the new code works as expected or its > broken. That's why I asked for an "IDR test suite": I wanted to test potential regressions. > If it works its good enough for all IDR users, if its broken we > should fix it. Seems simple enough.. am I missing something obvious? > Regards, Nadia