From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f54.google.com (mail-pb0-f54.google.com [209.85.160.54]) by kanga.kvack.org (Postfix) with ESMTP id 211DF6B0036 for ; Mon, 16 Jun 2014 01:19:15 -0400 (EDT) Received: by mail-pb0-f54.google.com with SMTP id un15so988138pbc.13 for ; Sun, 15 Jun 2014 22:19:14 -0700 (PDT) Received: from lgemrelse6q.lge.com (LGEMRELSE6Q.lge.com. [156.147.1.121]) by mx.google.com with ESMTP id cc3si12410861pad.47.2014.06.15.22.19.13 for ; Sun, 15 Jun 2014 22:19:14 -0700 (PDT) Date: Mon, 16 Jun 2014 14:23:25 +0900 From: Joonsoo Kim Subject: Re: [PATCH v2 05/10] DMA, CMA: support arbitrary bitmap granularity Message-ID: <20140616052325.GC23210@js1304-P5Q-DELUXE> References: <1402543307-29800-1-git-send-email-iamjoonsoo.kim@lge.com> <1402543307-29800-6-git-send-email-iamjoonsoo.kim@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Michal Nazarewicz Cc: Andrew Morton , "Aneesh Kumar K.V" , Marek Szyprowski , Minchan Kim , Russell King - ARM Linux , Greg Kroah-Hartman , Paolo Bonzini , Gleb Natapov , Alexander Graf , Benjamin Herrenschmidt , Paul Mackerras , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org On Thu, Jun 12, 2014 at 12:19:54PM +0200, Michal Nazarewicz wrote: > On Thu, Jun 12 2014, 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 > > Acked-by: Michal Nazarewicz > > > 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; > > Have you considered replacing count with maxno? No, I haven't. I think that count is better than maxno, since it represent number of pages in this region. > > > unsigned long *bitmap; > > + int order_per_bit; /* Order of pages represented by one bit */ > > I'd make it unsigned. Will fix it. > > struct mutex lock; > > }; > > > > +static void clear_cma_bitmap(struct cma *cma, unsigned long pfn, int > > count) > > For consistency cma_clear_bitmap would make more sense I think. On the > other hand, you're just moving stuff around so perhaps renaming the > function at this point is not worth it any more. Will fix it. > > +{ > > + unsigned long bitmapno, nr_bits; > > + > > + bitmapno = (pfn - cma->base_pfn) >> cma->order_per_bit; > > + nr_bits = cma_bitmap_pages_to_bits(cma, count); > > + > > + mutex_lock(&cma->lock); > > + bitmap_clear(cma->bitmap, bitmapno, nr_bits); > > + mutex_unlock(&cma->lock); > > +} > > + > > static int __init cma_activate_area(struct cma *cma) > > { > > - int bitmap_size = BITS_TO_LONGS(cma->count) * sizeof(long); > > + int bitmap_maxno = cma_bitmap_maxno(cma); > > + int bitmap_size = BITS_TO_LONGS(bitmap_maxno) * sizeof(long); > > unsigned long base_pfn = cma->base_pfn, pfn = base_pfn; > > unsigned i = cma->count >> pageblock_order; > > struct zone *zone; > > bitmap_maxno is never used again, perhaps: > > + int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long); > > instead? Up to you. Okay!! Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org