From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Nazarewicz Date: Thu, 12 Jun 2014 10:19:54 +0000 Subject: Re: [PATCH v2 05/10] DMA, CMA: support arbitrary bitmap granularity Message-Id: List-Id: References: <1402543307-29800-1-git-send-email-iamjoonsoo.kim@lge.com> <1402543307-29800-6-git-send-email-iamjoonsoo.kim@lge.com> In-Reply-To: <1402543307-29800-6-git-send-email-iamjoonsoo.kim@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: Joonsoo Kim , Andrew Morton , "Aneesh Kumar K.V" , Marek Szyprowski Cc: 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, Joonsoo Kim 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? > unsigned long *bitmap; > + int order_per_bit; /* Order of pages represented by one bit */ I'd make it unsigned. > 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. > +{ > + 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. -- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michał “mina86” Nazarewicz (o o) ooo +------ooO--(_)--Ooo--