[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] tracing/events: Add bounce tracing to swiotbl-xen
On 23/08/13 13:55, Konrad Rzeszutek Wilk wrote: On Thu, Aug 22, 2013 at 10:47:28PM +0100, Zoltan Kiss wrote: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-xen: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 (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.Could this be in the lib/swiotlb.c instead? You mean instead of drivers/xen/swiotlb-xen.c ? This is a Xen SWIOTLB specific thing, it will hit exactly at the point when double buffering becomes sure - under Xen. But I can rename the tracer and call trace_bounced in swiotlb_map_page as well, so it can be used for normal SWIOTLB bounce tracing as well. Is it OK for you? Regards, Zoli _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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