USB: xhci: Performance - move functions that find ep ring.

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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: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

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Sarah Sharp 2010-07-29 22:12:20 -07:00 • committed by Greg Kroah-Hartman

parent c6ba1c2af2

commit 021bff9179

4 changed files with 85 additions and 48 deletions

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43

drivers/usb/host/xhci-mem.c

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44

drivers/usb/host/xhci-ring.c

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41

drivers/usb/host/xhci.c

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5

drivers/usb/host/xhci.h

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