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Re: [quicwg/base-drafts] Byte counting at Congestion avoidance (#3917)

Jana Iyengar <notifications@github.com> Tue, 28 July 2020 01:55 UTC

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Date: Mon, 27 Jul 2020 18:54:59 -0700
From: Jana Iyengar <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] Byte counting at Congestion avoidance (#3917)
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@janaiyengar commented on this pull request.



> +      bytes_acked += acked_packet.sent_bytes
+      if (bytes_acked >= congestion_window):
+        bytes_acked -= congestion_window
+        congestion_window += max_datagram_size

I don't see how this is packet-based computation. Yes, the cwnd is incremented only when it can be incremented in max_datagram_size chunks, but at any given time, you know exactly what your fractional component is: (bytes_acked/congestion_window). At any given point in time, your total send allowance, in bytes, is (congestion_window + bytes_acked * max_datagram_size / congestion_window).

This fractional difference only matters if you are sending packets smaller than max_datagram_size.

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