From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konstantin Khlebnikov Subject: [PATCH] tcp_nv: use do_div() instead of expensive div64_u64() Date: Thu, 02 Nov 2017 17:07:05 +0300 Message-ID: <150963162556.169720.4979222608705024316.stgit@buzz> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , Lawrence Brakmo , linux-kernel@vger.kernel.org, Eric Dumazet To: netdev@vger.kernel.org, "David S. Miller" Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Average RTT is 32-bit thus full 64-bit division is redundant. Signed-off-by: Konstantin Khlebnikov Suggested-by: Stephen Hemminger Suggested-by: Eric Dumazet --- net/ipv4/tcp_nv.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp_nv.c b/net/ipv4/tcp_nv.c index 125fc1450b01..17e290ffcd80 100644 --- a/net/ipv4/tcp_nv.c +++ b/net/ipv4/tcp_nv.c @@ -209,7 +209,7 @@ static void tcpnv_acked(struct sock *sk, const struct ack_sample *sample) struct tcp_sock *tp = tcp_sk(sk); struct tcpnv *ca = inet_csk_ca(sk); unsigned long now = jiffies; - s64 rate64 = 0; + u64 rate64; u32 rate, max_win, cwnd_by_slope; u32 avg_rtt; u32 bytes_acked = 0; @@ -251,8 +251,9 @@ 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 ?: 1) * 100); + rate64 = ((u64)sample->in_flight) * 80000; + do_div(rate64, avg_rtt ?: 1); + rate = (u32)rate64; /* Remember the maximum rate seen during this RTT * Note: It may be more than one RTT. This function should be