From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752916AbcA0Eir (ORCPT ); Tue, 26 Jan 2016 23:38:47 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:60720 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751994AbcA0Ein (ORCPT ); Tue, 26 Jan 2016 23:38:43 -0500 Date: Tue, 26 Jan 2016 20:40:13 -0800 From: Andrew Morton To: Joonsoo Kim Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Jesper Dangaard Brouer , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 00/16] mm/slab: introduce new freed objects management way, OBJFREELIST_SLAB Message-Id: <20160126204013.a065301b.akpm@linux-foundation.org> In-Reply-To: <1452749069-15334-1-git-send-email-iamjoonsoo.kim@lge.com> References: <1452749069-15334-1-git-send-email-iamjoonsoo.kim@lge.com> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 14 Jan 2016 14:24:13 +0900 Joonsoo Kim wrote: > This patchset implements new freed object management way, that is, > OBJFREELIST_SLAB. Purpose of it is to reduce memory overhead in SLAB. > > SLAB needs a array to manage freed objects in a slab. If there is > leftover after objects are packed into a slab, we can use it as > a management array, and, in this case, there is no memory waste. > But, in the other cases, we need to allocate extra memory for > a management array or utilize dedicated internal memory in a slab for it. > Both cases causes memory waste so it's not good. > > With this patchset, freed object itself can be used for a management > array. So, memory waste could be reduced. Detailed idea and numbers > are described in last patch's commit description. Please refer it. > > In fact, I tested another idea implementing OBJFREELIST_SLAB with > extendable linked array through another freed object. It can remove > memory waste completely but it causes more computational overhead > in critical lock path and it seems that overhead outweigh benefit. > So, this patchset doesn't include it. I will attach prototype just for > a reference. It appears that this patchset is perhaps due a couple of touchups from Christoph's comments. I'll grab it as-is as I want to get an mmotm into linux-next tomorrow then vanish for a few days.