USB: xhci: Performance - move functions that find ep ring.
I've been using perf to measure the top symbols while transferring 1GB of data on a USB 3.0 drive with dd. This is using the raw disk with /dev/sdb, with a block size of 1K. During performance testing, the top symbol was xhci_triad_to_transfer_ring(), a function that should return immediately if streams are not enabled for an endpoint. It turned out that the functions to find the endpoint ring was defined in xhci-mem.c and used in xhci-ring.c and xhci-hcd.c. I moved a copy of xhci_triad_to_transfer_ring() and xhci_urb_to_transfer_ring() into xhci-ring.c and declared them static. I also made a static version of xhci_urb_to_transfer_ring() in xhci.c. This improved throughput on a 1GB read of the raw disk with dd from 186MB/s to 195MB/s, and perf reported sampling the xhci_triad_to_transfer_ring() 0.06% of the time, rather than 9.26% of the time. Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
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