Re: question about 3sec timeouts with tcp

[H. Willstrand]

On Tue, Apr 1, 2008 at 5:43 PM, Gabriel Barazer <gabriel@xxxxxxxx> wrote:
>
> On 04/01/2008 4:43:20 PM +0200, Brett Paden <paden@xxxxxxxxxxxx> wrote:
>  >> If I'm right Brett's problem relays in the test client (provided in
>  >> the first mail). This has probably to do with the number of ports
>  >> opened and closed during a short time period.
>  >
>  > My test client is designed to simulate the sort of load our production
>  > databases and web servers see.  We're talking on the order of 100-400
>  > connections per second.  On an unloaded server the 3000ms occur right
>  > around 400 connections a second but we have seen them a lower connection
>  > rates.  Are you suggesting that we could do something simple (like reap
>  > TIME_WAIT connections) to allevaite the problem?
>
>  Using tcp_tw_recycle / tcp_tw_reuse doesn't solve the problem either on
>  the client nor on the server. I tested with and without these options
>  enabled, disabled netfilter's connection tracking and none solved this
>  delay. If even the "lo" interface is concerned, there is definitely
>  something into the network stack and not the device drivers.
>
>  Here is a thread I started on LKML about this very same bug.
>  http://lkml.org/lkml/2008/3/14/353
>  There is a forum thread with french hosting providers talking about it.
>  (if some of you read french:
>  http://www.webmasterclub.fr/forum/topic,59486,0.html)
>
>  We are far from being alone!
>
>  Gabriel
>

Ok, seams to be the same issue that Leo has (has nothing to do with
the Brett / Marlon issue, only common dominator is the 3000ms).
This issue is probably caused by server delivering as miscalculated
SYN/ACK (the acked number is miscalculated, see my second mail).

I can't reproduce this, maybe I have failed in the server stressing.

// HW
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