From: Eric Dumazet <eric.dumazet@gmail.com>
To: Dave Taht <dave.taht@gmail.com>
Cc: codel@lists.bufferbloat.net, "Dave Täht" <dave.taht@bufferbloat.net>
Subject: Re: [Codel] [RFC PATCH] Codel: Enable packet drop with ECN-marked packets on a threshold
Date: Mon, 18 Jun 2012 04:58:26 +0200 [thread overview]
Message-ID: <1339988306.7491.306.camel@edumazet-glaptop> (raw)
In-Reply-To: <CAA93jw5X3BHfC_Yv=QCn+6sRf66UppLHaDbNOKEZoX-e1-QKsw@mail.gmail.com>
On Sun, 2012-06-17 at 22:40 -0400, Dave Taht wrote:
> On Sun, Jun 17, 2012 at 10:17 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> > if (A && B && C)
> >
> > Even if (C) is false, but A is true, B is evaluated.
>
> A is always true (or always false)
> B in this case is usually false except on the kinds of ECN-heavy
> workloads that exposed this issue
> and C is probably higher overhead than A or B
>
> So a better conditional is possible...
Not only better, but _correct_ ;)
To have a chance to be correct, your patch should have been :
if (params->ecn &&
vars->ldelay <= 2 * params->target &&
INET_ECN_set_ce(skb))
Because INET_ECN_set_ce(skb) is _doing_ ecn marking, and returns true is
ECN was successfully applied to the packet.
next prev parent reply other threads:[~2012-06-18 2:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-17 22:30 Dave Täht
2012-06-18 2:17 ` Eric Dumazet
2012-06-18 2:40 ` Dave Taht
2012-06-18 2:58 ` Eric Dumazet [this message]
2012-06-18 3:01 ` Dave Taht
2012-06-18 3:10 ` Eric Dumazet
2012-06-18 3:21 ` Dave Taht
2012-06-18 3:50 ` Dave Taht
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