Re: [rtcweb] Some language on "prioritization"

Harald Alvestrand <> Fri, 04 April 2014 08:51 UTC

Return-Path: <>
Received: from localhost ( []) by (Postfix) with ESMTP id 899C91A0453 for <>; Fri, 4 Apr 2014 01:51:57 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.909
X-Spam-Status: No, score=-1.909 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HTML_MESSAGE=0.001, T_RP_MATCHES_RCVD=-0.01] autolearn=ham
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id bnPj_jZAXEue for <>; Fri, 4 Apr 2014 01:51:52 -0700 (PDT)
Received: from ( []) by (Postfix) with ESMTP id BA6A91A0452 for <>; Fri, 4 Apr 2014 01:51:52 -0700 (PDT)
Received: from localhost (localhost []) by (Postfix) with ESMTP id 6FEFE7C5267; Fri, 4 Apr 2014 10:51:47 +0200 (CEST)
X-Virus-Scanned: Debian amavisd-new at
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id qLb5GVkKubeP; Fri, 4 Apr 2014 10:51:46 +0200 (CEST)
Received: from [] ( []) by (Postfix) with ESMTPSA id 953EC7C5266; Fri, 4 Apr 2014 10:51:45 +0200 (CEST)
Message-ID: <>
Date: Fri, 04 Apr 2014 10:51:43 +0200
From: Harald Alvestrand <>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0
MIME-Version: 1.0
To: Michael Tuexen <>
References: <> <> <>, <> <> <00af01cf4f59$fa617b90$ef2472b0$> <>
In-Reply-To: <>
X-Enigmail-Version: 1.6
Content-Type: multipart/alternative; boundary="------------000409000804030407070504"
Subject: Re: [rtcweb] Some language on "prioritization"
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Fri, 04 Apr 2014 08:51:57 -0000

I assume this is the scheduler envisioned in -ndata:

      SCTP_SS_PRIORITY:  Scheduling with different priorities is used.
         Streams having a higher priority will be scheduled first and
         when multiple streams have the same priority, the default
         scheduling should be used for them.  The priority can be
         assigned with the sctp_stream_value struct.  The higher the
         assigned value, the lower the priority, that is the default
         value 0 is the highest priority and therefore the default
         scheduling will be used if no priorities have been assigned.

This sounds like a "strict" scheduler, in that higher priority queues
will starve out lower priority ones completely. I remember having the
discussion at an IETF meeting about whether we wanted a "strict"
scheduler or a "weighted round robin" scheduler for this, but I wouldn't
trust my memory with what the conclusion was.

Was the conclusion that we should do "strict" scheduling? If so, it may
be best to make that consistent across the board - I had written in a
"weighted" scheduler for media into the prioritization text that I
started this thread with, but I think there's value to consistency.

(Note: -ndata has SS_PRIORITY in one place and SS_PRIO / SS_PRIO_INTER
in another place. Is there a subtlety here I'm not seeing?)