From: Stephen Hemminger <[email protected]> Date: Mon, 11 Dec 2017 08:58:11 -0800
> On Mon, 11 Dec 2017 21:26:41 +0800 > yuan linyu <[email protected]> wrote: > >> From: yuan linyu <[email protected]> >> >> Signed-off-by: yuan linyu <[email protected]> >> --- >> drivers/net/tap.c | 6 +----- >> 1 file changed, 1 insertion(+), 5 deletions(-) >> >> diff --git a/drivers/net/tap.c b/drivers/net/tap.c >> index 0a886fda..78900a0 100644 >> --- a/drivers/net/tap.c >> +++ b/drivers/net/tap.c >> @@ -275,11 +275,7 @@ static struct tap_queue *tap_get_queue(struct tap_dev >> *tap, >> >> if (likely(skb_rx_queue_recorded(skb))) { >> rxq = skb_get_rx_queue(skb); >> - >> - while (unlikely(rxq >= numvtaps)) >> - rxq -= numvtaps; >> - >> - queue = rcu_dereference(tap->taps[rxq]); >> + queue = rcu_dereference(tap->taps[rxq % numvtaps]); >> goto out; >> } >> > > Modulus is slower than the loop. Agreed, the loop is there intentionally. We do this in other areas of the kernel as well.
