Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932533AbaFLHIG (ORCPT ); Thu, 12 Jun 2014 03:08:06 -0400 Received: from lgeamrelo04.lge.com ([156.147.1.127]:46780 "EHLO lgeamrelo04.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932393AbaFLHIC (ORCPT ); Thu, 12 Jun 2014 03:08:02 -0400 X-Original-SENDERIP: 10.177.220.169 X-Original-MAILFROM: minchan@kernel.org Date: Thu, 12 Jun 2014 16:08:11 +0900 From: Minchan Kim To: Joonsoo 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: <20140612070811.GI12415@bbox> 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: <1402543307-29800-6-git-send-email-iamjoonsoo.kim@lge.com> 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 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. ;-) > struct page *page = NULL; > int ret; > > @@ -358,18 +386,19 @@ static struct page *__dma_alloc_from_contiguous(struct cma *cma, int count, > if (!count) > return NULL; > > - mask = (1 << align) - 1; > - > + mask = cma_bitmap_aligned_mask(cma, align); > + bitmap_maxno = cma_bitmap_maxno(cma); > + nr_bits = cma_bitmap_pages_to_bits(cma, count); > > for (;;) { > mutex_lock(&cma->lock); > - pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count, > - start, count, mask); > - if (pageno >= cma->count) { > + bitmapno = bitmap_find_next_zero_area(cma->bitmap, > + bitmap_maxno, start, nr_bits, mask); > + if (bitmapno >= bitmap_maxno) { > mutex_unlock(&cma->lock); > break; > } > - bitmap_set(cma->bitmap, pageno, count); > + bitmap_set(cma->bitmap, bitmapno, nr_bits); > /* > * It's safe to drop the lock here. We've marked this region for > * our exclusive use. If the migration fails we will take the > @@ -377,7 +406,7 @@ static struct page *__dma_alloc_from_contiguous(struct cma *cma, int count, > */ > mutex_unlock(&cma->lock); > > - pfn = cma->base_pfn + pageno; > + pfn = cma->base_pfn + (bitmapno << cma->order_per_bit); > mutex_lock(&cma_mutex); > ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA); > mutex_unlock(&cma_mutex); > @@ -392,7 +421,7 @@ static struct page *__dma_alloc_from_contiguous(struct cma *cma, int count, > pr_debug("%s(): memory range at %p is busy, retrying\n", > __func__, pfn_to_page(pfn)); > /* try again with a bit different memory target */ > - start = pageno + mask + 1; > + start = bitmapno + mask + 1; > } > > pr_debug("%s(): returned %p\n", __func__, page); > -- > 1.7.9.5 -- Kind regards, Minchan Kim -- 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/