From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerrit Renker Date: Fri, 12 Jan 2007 10:39:13 +0000 Subject: Re: [PATCH 1/1] DCCP: Fix up t_nom - FOLLOW-UP Message-Id: <200701121039.13177@strip-the-willow> List-Id: References: <200701101021.38920@strip-the-willow> In-Reply-To: <200701101021.38920@strip-the-willow> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: dccp@vger.kernel.org | Summary: I agree with Ian that hrtimer support is not required, and that= =20 | bursts are OK. =A0They are explicitly allowed by the RFC. I don't have much disagreement with your points. However, the `bursts' issue can really not be dismissed as unproblematic. Please see other reply. | =20 | > =A0 When a sender first starts sending at time t_0, it calculates t_ip= i, | > =A0 and calculates a nominal send time t_1 =3D t_0 + t_ipi for packet = 1. | > =A0 When the application becomes idle, it checks the current time, t_n= ow, | > =A0 and then requests re-scheduling after (t_ipi - (t_now - t_0)) | > =A0 seconds. =A0When the application is re-scheduled, it checks the cu= rrent | > =A0 time, t_now, again. =A0If (t_now > t_1 - delta) then packet 1 is s= ent. | >=20 | > Note that initially we set t_ipi to 1 second. This could be set to a | > better value based on connection setup as per Eddie and your | > discussion earlier but I haven't implemented this yet. In this way my | > code is a hack that I remove the 1 second and add the initial RTT once | > we obtain it. I see this ugliness can be removed when we make the code | > base conform to the RFC intent (it is not in RFC yet but Eddie said he | > would propose for revision) | =20 | For what it's worth, it's as close to in the RFC as it can get without a= =20 | revision. =A0The authors of the RFC agree that we meant the initial=20 | Request-Response RTT to be usable as an initial RTT estimate; the=20 | working group agreed; errata has been sent. So we are RFC-compliant for the moment. One point which remains unresolved = is, the above is about RTTs, but what about the initial sending rate of 1 packet per second, which implies an initial t_ipi of 1 second?