Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754765Ab3H1TRa (ORCPT ); Wed, 28 Aug 2013 15:17:30 -0400 Received: from mail-pa0-f51.google.com ([209.85.220.51]:61902 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754736Ab3H1TR2 (ORCPT ); Wed, 28 Aug 2013 15:17:28 -0400 Date: Wed, 28 Aug 2013 12:17:39 -0700 From: Kent Overstreet To: Andrew Morton Cc: "Nicholas A. Bellinger" , target-devel , lkml , "Michael S. Tsirkin" , Asias He , Jens Axboe , Tejun Heo , Ingo Molnar , Andi Kleen , Christoph Lameter , Oleg Nesterov , Christoph Lameter Subject: Re: [PATCH-v4 1/6] idr: Percpu ida Message-ID: <20130828191739.GD8032@kmo-pixel> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130827134314.7e9f8b792023eba41b4ea93d@linux-foundation.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1667 Lines: 31 On Tue, Aug 27, 2013 at 01:43:14PM -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! I remember seeing that email now, but somehow I completely missed all the review comments after the first one. Mea culpa! -- 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/