On Mon, Jun 24, 2013 at 6:24 PM, Oliver Neukum <oliver@xxxxxxxxxx> wrote: > On Monday 24 June 2013 17:42:05 Ming Lei wrote: >> All 4 transfer types can work well on EHCI HCD after switching to run >> URB giveback in tasklet context, so mark all HCD drivers to support >> it. >> >> At the same time, don't release ehci->lock during URB giveback, >> and remove the check on HCD_BH in ehci_disable_event(). >> >> From below test results on 3 machines(2 ARM and one x86), time >> consumed by EHCI interrupt handler droped much without performance >> loss. >> >> 1 test description >> 1.1 mass storage performance test: >> - run below command 10 times and compute the average performance >> >> dd if=/dev/sdN iflag=direct of=/dev/null bs=200M count=1 > > It would be nice to get worst case numbers. How bad does it get > if you reduce the sg size in usb-storage from 120K to 4K? A quick test on one arm A15 box shows that the average speed over 10 times 'dd' becomes 8.0MB/sec from 8.160MB/sec when 'bs' parameter of 'dd' changes to 4K, so there is ~1.9% performance loss with the patch under the worst case. Same test on my T410(x86), the speed difference is only 40K. I will collect the worst case numbers and include it in the commit log of V3. Thanks, -- Ming Lei -- 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
