[Bloat] Best practices for paced TCP on Linux?
dave.taht at gmail.com
Sat Apr 7 11:50:24 PDT 2012
Steinar: Judging from these results it sounds like you should try
limiting the send window.
I don't know what the right number is, or what the current calculation
for what percentage
of this is used for window related buffering, (anyone?) but reducing
the defaults by a lot for your tcp based video servers seems
like a good idea.
to do that, edit /etc/sysctl.conf, add or change the line for
net.core.wmem_max = 256000 # or less. or more. 5Mbit stream...fairly
short rtts... hmm.. no brain cells. no sleep. ?
This is another parameter that may apply, the last value should be changed.
net.ipv4.tcp_wmem = 4096 65536 2097152
These of course change it globally. you commit the changes with sysctl
-a -p /etc/sysctl.conf
You can also tweak SO_SNDBUF in vlc via setsockopt
64-256k seems about right but the math is eluding me this morning.
You can turn off window scaling entirely, but that's not the right answer
net.ipv4.tcp_default_win_scale = 0
the periodicity bothers me, it would be bad if that was synchronised,
to look at that problem would require some synchronous captures from
On Sat, Apr 7, 2012 at 11:10
AM, Steinar H. Gunderson <sgunderson at bigfoot.com> wrote:
> On Sat, Apr 07, 2012 at 08:10:50PM +0300, Jonathan Morton wrote:
>> 12Mbps ADSL2+ in Finland (not at all far from Norway), via a standard
>> modem-router rather than my usual Linux system. The LAN segment is
>> entirely wired full-duplex Ethernet. The receiver is a Core i7 Windows PC
>> running the latest stable VLC, so it's not short of ability to play what it
>> And it's dropping more frames than it's playing.
> Have you tried the one at cesur.tg12? It's pacing things out a bit more.
> /* Steinar */
> Homepage: http://www.sesse.net/
US Tel: 1-239-829-5608
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