Date: Mon, 18 Apr 2016 01:33:08 +0000 From: "sepherosa_gmail.com (Sepherosa Ziehau)" <phabric-noreply@FreeBSD.org> To: freebsd-net@freebsd.org Subject: [Differential] [Commented On] D5872: tcp: Don't prematurely drop receiving-only connections Message-ID: <a326620029270b35104b7b595dfe91a0@localhost.localdomain> In-Reply-To: <differential-rev-PHID-DREV-5vu7wrfibtoing77xfvt-req@FreeBSD.org> References: <differential-rev-PHID-DREV-5vu7wrfibtoing77xfvt-req@FreeBSD.org>
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sepherosa_gmail.com added a comment. In https://reviews.freebsd.org/D5872#127243, @hiren wrote: > In https://reviews.freebsd.org/D5872#127123, @jtl wrote: > > > > > > > > > The key feature that makes the retransmit timer inappropriate for an ACK-only case is that it is only stopped when we receive input; however, in the ACK-only case, we really want to stop it as soon as we transmit a successful ACK. > > Indeed. I guess we want to treat internal insufficient memory error with retransmit timer remedy. One would also argue that do you really want to go on when you failed to respond (with the ACK) for these many times. Don't you have bigger problems by now? As I said, it's _not_ continuous loosing of ACK due to ENOBUFS, but _intermittent_ (e.g. you lost 12 ACKs due to ENOBUFS in 2~3 hours) losing ACKs due to ENOBUFS is sufficient to kill a a long living receiving only connection. >> Of course, we could just drop the ACK and everything would "just work". But, it //probably// is still a good idea to try to re-transmit the ACK. > > I am not opposed to the suggested patch but its just...weird. (Also if its not obvious, I don't have a better solution to present. :-)) REVISION DETAIL https://reviews.freebsd.org/D5872 EMAIL PREFERENCES https://reviews.freebsd.org/settings/panel/emailpreferences/ To: sepherosa_gmail.com, network, glebius, lstewart, adrian, delphij, decui_microsoft.com, honzhan_microsoft.com, howard0su_gmail.com, freebsd-net-list, transport, jtl, hiren Cc: mike-karels.net, jtl
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