From: Neal Cardwell <ncardwell@google.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>,
Julian Anastasov <ja@ssi.bg>, David Miller <davem@davemloft.net>,
Yuchung Cheng <ycheng@google.com>,
netdev <netdev@vger.kernel.org>, Larry Brakmo <brakmo@google.com>
Subject: Re: [PATCH v6 net-next 2/2] tcp: switch rtt estimations to usec resolution
Date: Tue, 25 Feb 2014 12:46:40 -0500 [thread overview]
Message-ID: <CADVnQymGQ6V_28MTu02Yo7XjQz5OvmkbW3ozUvovhoz8g0rp=w@mail.gmail.com> (raw)
In-Reply-To: <1393309341.2316.120.camel@edumazet-glaptop2.roam.corp.google.com>
On Tue, Feb 25, 2014 at 1:22 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> Upcoming congestion controls for TCP require usec resolution for RTT
> estimations. Millisecond resolution is simply not enough these days.
...
> ---
> v6: Do not use ktime_get() but skb_mstamp, as Stephen Hemminger pointed
> out some platforms have slow ktime_get()
...
>
> - ca_ops->pkts_acked(sk, pkts_acked, rtt_us);
> - }
> - } else if (skb && rtt_update && sack_rtt >= 0 &&
> - sack_rtt > (s32)(now - TCP_SKB_CB(skb)->when)) {
> + } else if (skb && rtt_update && sack_rtt_us >= 0 &&
> + sack_rtt_us > skb_mstamp_us_delta(&now, &skb->skb_mstamp)) {
This gets rid of the (s32) cast for the result of the time
subtraction. Is that safe?
The rest looks great to me!
neal
next prev parent reply other threads:[~2014-02-25 17:46 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-23 6:38 [PATCH net-next] tcp: switch rtt estimations to usec resolution Eric Dumazet
2014-02-23 7:36 ` Julian Anastasov
2014-02-23 17:55 ` Eric Dumazet
2014-02-23 18:50 ` [PATCH v2 " Eric Dumazet
2014-02-23 19:19 ` Yuchung Cheng
2014-02-23 21:41 ` Eric Dumazet
2014-02-24 4:42 ` [PATCH v3 " Eric Dumazet
2014-02-24 17:58 ` Eric Dumazet
2014-02-24 18:24 ` [PATCH v4 " Eric Dumazet
2014-02-24 20:47 ` Julian Anastasov
2014-02-24 22:13 ` Eric Dumazet
2014-02-24 23:01 ` Julian Anastasov
2014-02-24 23:31 ` [PATCH v5 " Eric Dumazet
2014-02-24 23:51 ` Stephen Hemminger
2014-02-25 0:15 ` David Miller
2014-02-25 1:11 ` Eric Dumazet
2014-02-25 1:38 ` Eric Dumazet
2014-02-25 6:22 ` [PATCH v6 net-next 1/2] net: add skb_mstamp infrastructure Eric Dumazet
2014-02-25 9:51 ` David Laight
2014-02-25 12:21 ` Eric Dumazet
2014-02-26 20:02 ` David Miller
2014-02-26 20:29 ` Eric Dumazet
2014-02-26 22:02 ` [PATCH v7 " Eric Dumazet
2014-02-26 22:04 ` David Miller
2014-02-25 6:22 ` [PATCH v6 net-next 2/2] tcp: switch rtt estimations to usec resolution Eric Dumazet
2014-02-25 17:46 ` Neal Cardwell [this message]
2014-02-25 18:17 ` Eric Dumazet
2014-02-25 19:13 ` Neal Cardwell
2014-02-26 22:02 ` [PATCH v7 " Eric Dumazet
2014-02-26 22:04 ` David Miller
2014-02-27 1:09 ` Stephen Hemminger
2014-02-27 1:21 ` Rick Jones
2014-02-27 9:57 ` David Laight
2014-02-27 2:25 ` Eric Dumazet
2014-02-24 22:19 ` [PATCH v4 net-next] " Eric Dumazet
2014-02-28 5:20 ` [PATCH v2 " Andi Kleen
2014-02-28 6:14 ` Eric Dumazet
2014-02-28 13:31 ` Andi Kleen
2014-02-28 13:51 ` Eric Dumazet
2014-02-23 19:11 ` [PATCH " Julian Anastasov
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