Messages in this thread | | | Date | Thu, 27 May 1999 07:46:18 -0400 (EDT) | From | jamal <> | Subject | Re: [patch] TCP/IP delacks disabled with MPI |
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>cwnd=1 (measured in segments) >1-byte payload => 41 byte TCP packet >36*41=1476 bytes < MSS=1500 bytes (the initial congestion window)
>So rfc2001 would allow 36 tiny packets to be sent when cwnd=1, but Linux >2.2.2 test reads
>if(tcp_packets_in_flight(tp) >= tp->snd_cwnd)
>and since 36 >= 1, Linux would not allow this. In fact, Linux would
Looks like packet counting fails in this specific situation. However, I think your interpretation is slightly biased. Using your arguement, the initial cwnd (1 MSS) should be 36 packets (without applying the RFC2414 initial window cap).
It would be a good idea to avoid per-packet computation introduced by Andrea's new patch (i think there are a lot more people who are *not* MPI users). Could the problem be resolved by setting the sender MSS to be very small (eg SMSS=64 bytes in the example you provide -- and maintain the old fix)? I am not sure what effects that will have on PMTU.
Your app should also ensure that the TOS is marked such that your packet is queued on the highest prioirity queue (using the default three band scheduler).
cheers, jamal
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