Re: Possible BUG in IPv4 TCP window handling, all recent 2.4.x/2.6.x kernels
From: Ion Badulescu <hidden>
Date: 2005-09-28 16:31:55
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Hi Alexey, On Fri, 2 Sep 2005, Alexey Kuznetsov wrote:
quoted hunk ↗ jump to hunk
Anyway, ignoring this puzzle, the following patch for 2.4 should help.--- net/ipv4/tcp_input.c.orig 2003-02-20 20:38:39.000000000 +0300 +++ net/ipv4/tcp_input.c 2005-09-02 22:28:00.845952888 +0400@@ -343,8 +343,6 @@app_win -= tp->ack.rcv_mss; app_win = max(app_win, 2U*tp->advmss); - if (!ofo_win) - tp->window_clamp = min(tp->window_clamp, app_win); tp->rcv_ssthresh = min(tp->window_clamp, 2U*tp->advmss); } }
I'm very happy to report that the above patch, applied to 2.6.12.6, seems to have cured the TCP window problem we were experiencing. I've been testing it extensively over the last 4 weeks, and I have yet to see any repeats of the previous behavior. The TCP window now usually settles to around 4k (unscaled, 16k scaled), which is smallish but good enough for our purposes. Thanks, -Ion