From 2b2b614dd24e4e6474fcf2dcf69c95c908838959 Mon Sep 17 00:00:00 2001 From: Zoltan Kiss Date: Wed, 4 Sep 2013 21:11:05 +0100 Subject: tracing/events: Add bounce tracing to swiotbl Ftrace is currently not able to detect when SWIOTLB has to do double buffering. Under Xen you can only see it indirectly in function_graph, when xen_swiotlb_map_page() doesn't stop after range_straddles_page_boundary(), but calls spinlock functions, memcpy() and xen_phys_to_bus() as well. This patch introduces the swiotlb:swiotlb_bounced event, which also prints out the following informations to help you find out why bouncing happened: dev_name: 0000:08:00.0 dma_mask=ffffffffffffffff dev_addr=9149f000 size=32768 swiotlb_force=0 If you use Xen, and (dev_addr + size + 1) > dma_mask, the buffer is out of the device's DMA range. If swiotlb_force == 1, you should really change the kernel parameters. Otherwise, the buffer is not contiguous in mfn space. Signed-off-by: Zoltan Kiss [v1: Don't print 'swiotlb_force=X', just print swiotlb_force if it is enabled] Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/swiotlb-xen.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'drivers/xen/swiotlb-xen.c') diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c index 1b2277c311d2..b31081007a81 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -42,6 +42,9 @@ #include #include #include + +#define CREATE_TRACE_POINTS +#include /* * Used to do a quick range check in swiotlb_tbl_unmap_single and * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this @@ -358,6 +361,8 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, /* * Oh well, have to allocate and map a bounce buffer. */ + trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force); + map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir); if (map == SWIOTLB_MAP_ERROR) return DMA_ERROR_CODE; -- cgit v1.2.3