Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932702AbaFLHZZ (ORCPT ); Thu, 12 Jun 2014 03:25:25 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:45686 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S932161AbaFLHZT (ORCPT ); Thu, 12 Jun 2014 03:25:19 -0400 X-IronPort-AV: E=Sophos;i="5.00,694,1396972800"; d="scan'208";a="31801467" Message-ID: <539955E5.9070504@cn.fujitsu.com> Date: Thu, 12 Jun 2014 15:25:25 +0800 From: Zhang Yanfei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131030 Thunderbird/17.0.10 MIME-Version: 1.0 To: Minchan Kim CC: Joonsoo Kim , Andrew Morton , "Aneesh Kumar K.V" , Marek Szyprowski , Michal Nazarewicz , Russell King - ARM Linux , , , Gleb Natapov , Greg Kroah-Hartman , Alexander Graf , , , Paul Mackerras , Benjamin Herrenschmidt , Paolo Bonzini , , Subject: Re: [PATCH v2 05/10] DMA, CMA: support arbitrary bitmap granularity References: <1402543307-29800-1-git-send-email-iamjoonsoo.kim@lge.com> <1402543307-29800-6-git-send-email-iamjoonsoo.kim@lge.com> <20140612070811.GI12415@bbox> In-Reply-To: <20140612070811.GI12415@bbox> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.225.89] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/12/2014 03:08 PM, 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 > Acked-by: Minchan Kim > > Just a nit below. > >> >> 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 */ >> struct mutex lock; >> }; >> >> @@ -157,9 +158,38 @@ void __init dma_contiguous_reserve(phys_addr_t limit) >> >> static DEFINE_MUTEX(cma_mutex); >> >> +static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order) >> +{ >> + return (1 << (align_order >> cma->order_per_bit)) - 1; >> +} >> + >> +static unsigned long cma_bitmap_maxno(struct cma *cma) >> +{ >> + return cma->count >> cma->order_per_bit; >> +} >> + >> +static unsigned long cma_bitmap_pages_to_bits(struct cma *cma, >> + unsigned long pages) >> +{ >> + return ALIGN(pages, 1 << cma->order_per_bit) >> cma->order_per_bit; >> +} >> + >> +static void clear_cma_bitmap(struct cma *cma, unsigned long pfn, int count) >> +{ >> + 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; >> @@ -221,6 +251,7 @@ core_initcall(cma_init_reserved_areas); >> * @base: Base address of the reserved area optional, use 0 for any >> * @limit: End address of the reserved memory (optional, 0 for any). >> * @alignment: Alignment for the contiguous memory area, should be power of 2 >> + * @order_per_bit: Order of pages represented by one bit on bitmap. >> * @res_cma: Pointer to store the created cma region. >> * @fixed: hint about where to place the reserved area >> * >> @@ -235,7 +266,7 @@ core_initcall(cma_init_reserved_areas); >> */ >> static int __init __dma_contiguous_reserve_area(phys_addr_t size, >> phys_addr_t base, phys_addr_t limit, >> - phys_addr_t alignment, >> + phys_addr_t alignment, int order_per_bit, >> struct cma **res_cma, bool fixed) >> { >> struct cma *cma = &cma_areas[cma_area_count]; >> @@ -269,6 +300,8 @@ static int __init __dma_contiguous_reserve_area(phys_addr_t size, >> base = ALIGN(base, alignment); >> size = ALIGN(size, alignment); >> limit &= ~(alignment - 1); >> + /* size should be aligned with order_per_bit */ >> + BUG_ON(!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit)); >> >> /* Reserve memory */ >> if (base && fixed) { >> @@ -294,6 +327,7 @@ static int __init __dma_contiguous_reserve_area(phys_addr_t size, >> */ >> cma->base_pfn = PFN_DOWN(base); >> cma->count = size >> PAGE_SHIFT; >> + cma->order_per_bit = order_per_bit; >> *res_cma = cma; >> cma_area_count++; >> >> @@ -313,7 +347,7 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, >> { >> int ret; >> >> - ret = __dma_contiguous_reserve_area(size, base, limit, 0, >> + ret = __dma_contiguous_reserve_area(size, base, limit, 0, 0, >> res_cma, fixed); >> if (ret) >> return ret; >> @@ -324,13 +358,6 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, >> return 0; >> } >> >> -static void clear_cma_bitmap(struct cma *cma, unsigned long pfn, int count) >> -{ >> - mutex_lock(&cma->lock); >> - bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count); >> - mutex_unlock(&cma->lock); >> -} >> - >> /** >> * dma_alloc_from_contiguous() - allocate pages from contiguous area >> * @dev: Pointer to device for which the allocation is performed. >> @@ -345,7 +372,8 @@ static void clear_cma_bitmap(struct cma *cma, unsigned long pfn, int count) >> static struct page *__dma_alloc_from_contiguous(struct cma *cma, int count, >> unsigned int align) >> { >> - unsigned long mask, pfn, pageno, start = 0; >> + unsigned long mask, pfn, start = 0; >> + unsigned long bitmap_maxno, bitmapno, nr_bits; > > Just Nit: bitmap_maxno, bitmap_no or something consistent. > I know you love consistent when I read description in first patch > in this patchset. ;-) > Yeah, not only in this patchset, I saw Joonsoo trying to unify all kinds of things in the MM. This is great for newbies, IMO. -- Thanks. Zhang Yanfei -- 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/