On Wednesday 15 June 2005 06:09 pm, Anant Padmanath Mudambi wrote:
> Hi,
> If I write the value of a tunable parameter to the /proc/web100/<cid>
> file, how soon after that will the TCP stack be able to see and use this
> value. I am trying to add a tunable parameter to set the initial cwnd. For
> now I am using MaxSsthresh WAD parameter for setting the init cwnd value
> and setting cwnd to MaxSsthresh in tcp_input.c:reno_cong_avoid(). I was
> expecting that TCP would be able to use the init cwnd value as soon as it
> gets an ACK after the init cwnd value has been written to the
> /proc/web100/<cid> file, but that's not happening.
> Would anyone could tell me how a value written to /proc/web100/<cid> gets
> stored in the web100stats structure of the tcp_opt structure and how soon
> it is available to the TCP stack?
The MaxSsthresh value will be written by the time your write() call completes,
and is available to TCP immediately.
Are you sure that TCP is getting to reno_cong_avoid()? The default lately is
actually BIC instead of Reno.
-John
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