On Wed, 2017-11-01 at 16:32 +0300, Konstantin Khlebnikov wrote: > Average RTT could become zero. This happened in real life at least twice. > This patch treats zero as 1us. > > Signed-off-by: Konstantin Khlebnikov <khlebni...@yandex-team.ru> > --- > net/ipv4/tcp_nv.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/ipv4/tcp_nv.c b/net/ipv4/tcp_nv.c > index 1ff73982e28c..125fc1450b01 100644 > --- a/net/ipv4/tcp_nv.c > +++ b/net/ipv4/tcp_nv.c > @@ -252,7 +252,7 @@ static void tcpnv_acked(struct sock *sk, const struct > ack_sample *sample) > > /* rate in 100's bits per second */ > rate64 = ((u64)sample->in_flight) * 8000000; > - rate = (u32)div64_u64(rate64, (u64)(avg_rtt * 100)); > + rate = (u32)div64_u64(rate64, (u64)(avg_rtt ?: 1) * 100); > > /* Remember the maximum rate seen during this RTT > * Note: It may be more than one RTT. This function should be >
BTW, this div64_u64() could be replaced by a u32 divide (aka do_div()), slightly less expensive. rate64 = ((u64)sample->in_flight) * 80000; do_div(rate64, avg_rtt ?: 1); rate = (u32)rate64;
