On Mon, Jun 12, 2023 at 09:47:55AM +0200, Christoph Hellwig wrote: > On Mon, Jun 12, 2023 at 07:44:46AM +0000, Tomonori Fujita wrote: > > I cannot recall the patch but from quick look, moving trace_swiotlb_bounced() to > > swiotlb_tbl_map_single() makes sense. > > Agreed. There's actually two call-sites for trace_swiotlb_bounced(): swiotlb_map() and xen_swiotlb_map_page(). Both those functions also invoke swiotlb_tbl_map_single(), so moving the call to trace_swiotlb_bounced() to swiotlb_tbl_map_single() means that there will be 2 traces per bounce buffering event. The difference between the two call-sites of trace_swiotlb_bounced() is that the call in swiotlb_map() uses phys_to_dma() for the device address, while xen_swiotlb_map_page() uses xen_phys_to_dma(). Would it make sense to move the trace_swiotlb_bounced() call to swiotlb_tbl_map_single() and then introduce a swiotlb_tbl_map_single_notrace() function which doesn't do the tracing, and xen_swiotlb_map_page() can call this? --Isaac
