Issue with huge numbers of connections

Peter Jeremy peterjeremy at
Sun Jun 17 19:37:17 UTC 2007

On 2007-Jun-17 13:02:38 -0600, "M. Warner Losh" <imp at> wrote:
>Doing the math on 10^9 connections in a week translates to ~1650/s, so we'd
>expect there are on the order of 100-200 connections steady state at any
>time.  I suspect that the peak load may be up to 100 times that, which is
>still only 20000 connections.  The hangs don't seem to hang at a peak, but

Note that the TCP state machine includes a 2xMSL (128 second) timeout
after the connection closes before the kernel releases the TCP control
block.  There may not be many connections open but at 1650 connections
per second, there are about 200,000 control blocks in TCPS_TIME_WAIT -
far more if the load is peaky.

Peter Jeremy
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