From 5ee1af9f519e6dc5a7d7912e87a1aaec857c8818 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 8 Mar 2006 17:57:26 -0800 Subject: [PATCH] [PATCH] block: disable block layer bouncing for most memory on 64bit systems The low level PCI DMA mapping functions should handle it in most cases. This should fix problems with depleting the DMA zone early. The old code used precious GFP_DMA memory in many cases where it was not needed. Signed-off-by: Andi Kleen Cc: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- block/ll_rw_blk.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index 03d9c82b0f..0ef2971a9e 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -625,26 +625,31 @@ static inline int ordered_bio_endio(struct request *rq, struct bio *bio, * Different hardware can have different requirements as to what pages * it can do I/O directly to. A low level driver can call * blk_queue_bounce_limit to have lower memory pages allocated as bounce - * buffers for doing I/O to pages residing above @page. By default - * the block layer sets this to the highest numbered "low" memory page. + * buffers for doing I/O to pages residing above @page. **/ void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr) { unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT; - - /* - * set appropriate bounce gfp mask -- unfortunately we don't have a - * full 4GB zone, so we have to resort to low memory for any bounces. - * ISA has its own < 16MB zone. - */ - if (bounce_pfn < blk_max_low_pfn) { - BUG_ON(dma_addr < BLK_BOUNCE_ISA); + int dma = 0; + + q->bounce_gfp = GFP_NOIO; +#if BITS_PER_LONG == 64 + /* Assume anything <= 4GB can be handled by IOMMU. + Actually some IOMMUs can handle everything, but I don't + know of a way to test this here. */ + if (bounce_pfn < (0xffffffff>>PAGE_SHIFT)) + dma = 1; + q->bounce_pfn = max_low_pfn; +#else + if (bounce_pfn < blk_max_low_pfn) + dma = 1; + q->bounce_pfn = bounce_pfn; +#endif + if (dma) { init_emergency_isa_pool(); q->bounce_gfp = GFP_NOIO | GFP_DMA; - } else - q->bounce_gfp = GFP_NOIO; - - q->bounce_pfn = bounce_pfn; + q->bounce_pfn = bounce_pfn; + } } EXPORT_SYMBOL(blk_queue_bounce_limit); -- 2.39.5