I concur with Alan. If there is only a single instance of xhci_urb_to_transfer_ring(), it is more likely that this function will be resident in the processor's cache, making the opposite to be true; performance would improve based upon the number of times this function is called, object code notwithstanding. Pete Brink -----Original Message----- From: linux-usb-owner@xxxxxxxxxxxxxxx [mailto:linux-usb-owner@xxxxxxxxxxxxxxx] On Behalf Of Alan Stern Sent: Friday, October 28, 2011 8:11 AM To: Sarah Sharp Cc: Andiry Xu; linux-usb@xxxxxxxxxxxxxxx Subject: Re: [PATCH] xHCI: Remove duplicate functions On Fri, 28 Oct 2011, Sarah Sharp wrote: > On Fri, Oct 28, 2011 at 05:05:58PM +0800, Andiry Xu wrote: > > There're two static xhci_urb_to_transfer_ring() implementations in xhci.c > > and xhci-ring.c, and they do exactly the same things. > > > > Remove one of them to get rid of duplicate codes. > > NAK. There are the same functions in two separate files for performance > reasons. This function is used very often, and allowing it to be static > lets the compiler optimize it. Optimize it how? The only optimization for static functions that I'm aware of is to put them inline. But this function is sufficiently long and complicated that putting in inline would yield worse object code, not better. Have you measured the performance difference? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
