Re: Linux TCP - unexpected retransmissions

Francois <fpomerle@xxxxxx> wrote:
After browsing the Linux code for a while (I wish I understand it
better), we realized that the TCP stack optimizes performance by
separating the processing of events between user and kernel
space. We suspect that under certain conditions (heavy burst of
messages, or messages arriving at the same time), the stack drops or
postpones processing of events (holding locks, buffering) causing
timers to trigger retransmissions.

ISTR there is a sysctl which controls some of that decision making -
net.ipv4.tcp_low_latency . Maybe that will help, maybe not.

Quite frankly, TCP isn't exactly the right protocol for firm/hard
realtime requirements, as you have learned from experience with lost
traffic and retransmissions. There isn't really a "perfect" protocol
for such things though (IMO).

rick jones
--
a wide gulf separates "what if" from "if only"
these opinions are mine, all mine; HP might not want them anyway... :)
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