2b2b614dd2
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 <zoltan.kiss@citrix.com> [v1: Don't print 'swiotlb_force=X', just print swiotlb_force if it is enabled] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
47 lines
1.1 KiB
C
47 lines
1.1 KiB
C
#undef TRACE_SYSTEM
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#define TRACE_SYSTEM swiotlb
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#if !defined(_TRACE_SWIOTLB_H) || defined(TRACE_HEADER_MULTI_READ)
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#define _TRACE_SWIOTLB_H
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#include <linux/tracepoint.h>
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TRACE_EVENT(swiotlb_bounced,
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TP_PROTO(struct device *dev,
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dma_addr_t dev_addr,
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size_t size,
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int swiotlb_force),
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TP_ARGS(dev, dev_addr, size, swiotlb_force),
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TP_STRUCT__entry(
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__string( dev_name, dev_name(dev) )
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__field( u64, dma_mask )
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__field( dma_addr_t, dev_addr )
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__field( size_t, size )
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__field( int, swiotlb_force )
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),
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TP_fast_assign(
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__assign_str(dev_name, dev_name(dev));
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__entry->dma_mask = (dev->dma_mask ? *dev->dma_mask : 0);
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__entry->dev_addr = dev_addr;
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__entry->size = size;
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__entry->swiotlb_force = swiotlb_force;
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),
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TP_printk("dev_name: %s dma_mask=%llx dev_addr=%llx "
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"size=%zu %s",
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__get_str(dev_name),
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__entry->dma_mask,
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(unsigned long long)__entry->dev_addr,
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__entry->size,
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__entry->swiotlb_force ? "swiotlb_force" : "" )
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);
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#endif /* _TRACE_SWIOTLB_H */
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/* This part must be outside protection */
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#include <trace/define_trace.h>
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