Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753502Ab3H0Uvj (ORCPT ); Tue, 27 Aug 2013 16:51:39 -0400 Received: from mail.linux-iscsi.org ([67.23.28.174]:55036 "EHLO linux-iscsi.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752228Ab3H0Uvh (ORCPT ); Tue, 27 Aug 2013 16:51:37 -0400 Message-ID: <1377637118.32763.241.camel@haakon3.risingtidesystems.com> Subject: Re: [PATCH-v4 1/6] idr: Percpu ida From: "Nicholas A. Bellinger" To: Andrew Morton Cc: target-devel , lkml , "Michael S. Tsirkin" , Asias He , Kent Overstreet , Jens Axboe , Tejun Heo , Ingo Molnar , Andi Kleen , Christoph Lameter , Oleg Nesterov , Christoph Lameter Date: Tue, 27 Aug 2013 13:58:38 -0700 In-Reply-To: <20130827134314.7e9f8b792023eba41b4ea93d@linux-foundation.org> References: <1377634306-13981-1-git-send-email-nab@linux-iscsi.org> <1377634306-13981-2-git-send-email-nab@linux-iscsi.org> <20130827134314.7e9f8b792023eba41b4ea93d@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1731 Lines: 37 On Tue, 2013-08-27 at 13:43 -0700, Andrew Morton wrote: > On Tue, 27 Aug 2013 20:11:41 +0000 "Nicholas A. Bellinger" wrote: > > > Percpu frontend for allocating ids. With percpu allocation (that works), > > it's impossible to guarantee it will always be possible to allocate all > > nr_tags - typically, some will be stuck on a remote percpu freelist > > where the current job can't get to them. > > > > We do guarantee that it will always be possible to allocate at least > > (nr_tags / 2) tags - this is done by keeping track of which and how many > > cpus have tags on their percpu freelists. On allocation failure if > > enough cpus have tags that there could potentially be (nr_tags / 2) tags > > stuck on remote percpu freelists, we then pick a remote cpu at random to > > steal from. > > > > Note that there's no cpu hotplug notifier - we don't care, because > > steal_tags() will eventually get the down cpu's tags. We _could_ satisfy > > more allocations if we had a notifier - but we'll still meet our > > guarantees and it's absolutely not a correctness issue, so I don't think > > it's worth the extra code. > > Except for one silly trivial thing, all of my August 20 review comments > were ignored. You didn't even bother replying to the email. > Sorry, unfortunately this email didn't make it through Kent's email filter last week, and he responded to the thread yesterday. Kent, can you address Andrew's remaining comments please..? --nab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/