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Message-ID: <87fxbgf0qh.fsf@basil.nowhere.org> Date: Tue, 25 Aug 2009 16:04:54 +0200 From: Andi Kleen <andi@...stfloor.org> To: <Li_Xin2@....com> Cc: <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org Subject: Re: TCP keepalive timer problem <Li_Xin2@....com> writes: [cc netdev] > Greetings, > > I found one problem in Linux TCP keepalive timer processing, after > searching on google, I found Daniel Stempel reported the same problem in > 2007 (http://lkml.indiana.edu/hypermail/linux/kernel/0702.2/1136.html), > but got no answer. So I have to reraise it. > > Can anyone help answer this two-years long question? I think the idea behind the tcp_keepalive_timer check referrenced in the other mail is: when there are outstanding non acked packets then the normal retransmit timer will do keep alive because it will retransmit and retransmit in exponential backoff and eventually notice something is wrong. The obvious hole is that if the keepalive is shorter than the worst case retransmit timeout then you'll have to wait for the longer timeout. I presume that's what is happening for you? You set the keep alive timeout very low and expect the timeout to be very low, but it's 30+mins (default retransmit timeout)? -Andi -- ak@...ux.intel.com -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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