Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932290AbaFLGkA (ORCPT ); Thu, 12 Jun 2014 02:40:00 -0400 Received: from lgeamrelo02.lge.com ([156.147.1.126]:50494 "EHLO lgeamrelo02.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754586AbaFLGj6 (ORCPT ); Thu, 12 Jun 2014 02:39:58 -0400 X-Original-SENDERIP: 10.177.220.145 X-Original-MAILFROM: iamjoonsoo.kim@lge.com Date: Thu, 12 Jun 2014 15:43:55 +0900 From: Joonsoo Kim To: Minchan Kim Cc: Andrew Morton , "Aneesh Kumar K.V" , Marek Szyprowski , Michal Nazarewicz , Russell King - ARM Linux , kvm@vger.kernel.org, linux-mm@kvack.org, Gleb Natapov , Greg Kroah-Hartman , Alexander Graf , kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Mackerras , Benjamin Herrenschmidt , Paolo Bonzini , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 05/10] DMA, CMA: support arbitrary bitmap granularity Message-ID: <20140612064355.GC19918@js1304-P5Q-DELUXE> References: <1402543307-29800-1-git-send-email-iamjoonsoo.kim@lge.com> <1402543307-29800-6-git-send-email-iamjoonsoo.kim@lge.com> <20140612060610.GH12415@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140612060610.GH12415@bbox> 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 On Thu, Jun 12, 2014 at 03:06:10PM +0900, Minchan Kim wrote: > On Thu, Jun 12, 2014 at 12:21:42PM +0900, Joonsoo Kim wrote: > > ppc kvm's cma region management requires arbitrary bitmap granularity, > > since they want to reserve very large memory and manage this region > > with bitmap that one bit for several pages to reduce management overheads. > > So support arbitrary bitmap granularity for following generalization. > > > > Signed-off-by: Joonsoo Kim > > > > diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c > > index bc4c171..9bc9340 100644 > > --- a/drivers/base/dma-contiguous.c > > +++ b/drivers/base/dma-contiguous.c > > @@ -38,6 +38,7 @@ struct cma { > > unsigned long base_pfn; > > unsigned long count; > > unsigned long *bitmap; > > + int order_per_bit; /* Order of pages represented by one bit */ > > Hmm, I'm not sure it's good as *general* interface even though it covers > existing usecases. > > It forces a cma area should be handled by same size unit. Right? > It's really important point for this patchset's motivation so I will stop > review and wait other opinions. If you pass 0 to order_per_bit, you can manage cma area in every size(page unit) you want. If you pass certain number to order_per_bit, you can allocate and release cma area in multiple of such page order. I think that this is more general implementation than previous versions. Thanks. -- 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/