From 2b2b614dd24e4e6474fcf2dcf69c95c908838959 Mon Sep 17 00:00:00 2001 From: Zoltan Kiss Date: Wed, 4 Sep 2013 21:11:05 +0100 Subject: [PATCH] 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 ++++ include/trace/events/swiotlb.h | 46 ++++++++++++++++++++++++++++++++++ lib/swiotlb.c | 4 +++ 3 files changed, 55 insertions(+) create mode 100644 include/trace/events/swiotlb.h 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; diff --git a/include/trace/events/swiotlb.h b/include/trace/events/swiotlb.h new file mode 100644 index 000000000000..7ea4c5e7c448 --- /dev/null +++ b/include/trace/events/swiotlb.h @@ -0,0 +1,46 @@ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM swiotlb + +#if !defined(_TRACE_SWIOTLB_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_SWIOTLB_H + +#include + +TRACE_EVENT(swiotlb_bounced, + + TP_PROTO(struct device *dev, + dma_addr_t dev_addr, + size_t size, + int swiotlb_force), + + TP_ARGS(dev, dev_addr, size, swiotlb_force), + + TP_STRUCT__entry( + __string( dev_name, dev_name(dev) ) + __field( u64, dma_mask ) + __field( dma_addr_t, dev_addr ) + __field( size_t, size ) + __field( int, swiotlb_force ) + ), + + TP_fast_assign( + __assign_str(dev_name, dev_name(dev)); + __entry->dma_mask = (dev->dma_mask ? *dev->dma_mask : 0); + __entry->dev_addr = dev_addr; + __entry->size = size; + __entry->swiotlb_force = swiotlb_force; + ), + + TP_printk("dev_name: %s dma_mask=%llx dev_addr=%llx " + "size=%zu %s", + __get_str(dev_name), + __entry->dma_mask, + (unsigned long long)__entry->dev_addr, + __entry->size, + __entry->swiotlb_force ? "swiotlb_force" : "" ) +); + +#endif /* _TRACE_SWIOTLB_H */ + +/* This part must be outside protection */ +#include diff --git a/lib/swiotlb.c b/lib/swiotlb.c index 4e8686c7e5a4..f0d841907da6 100644 --- a/lib/swiotlb.c +++ b/lib/swiotlb.c @@ -38,6 +38,8 @@ #include #include +#include + #define OFFSET(val,align) ((unsigned long) \ ( (val) & ( (align) - 1))) @@ -726,6 +728,8 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page, if (dma_capable(dev, dev_addr, size) && !swiotlb_force) return dev_addr; + trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force); + /* Oh well, have to allocate and map a bounce buffer. */ map = map_single(dev, phys, size, dir); if (map == SWIOTLB_MAP_ERROR) { -- 2.39.2