Date: 04 Feb 1999 11:08:40 -0600 From: Joel Ray Holveck <joelh@gnu.org> To: Graham Wheeler <gram@cdsec.com> Cc: hackers@FreeBSD.ORG Subject: Re: TCP keepinit time and connection timeouts Message-ID: <86aeyuqep3.fsf@detlev.UUCP> In-Reply-To: Graham Wheeler's message of "Thu, 4 Feb 1999 14:51:10 %2B0200 (SAT)" References: <199902041251.OAA27910@cdsec.com>
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> We have noticed that the connect() timeout when the target host does not > respond is much shorter than the value specified by the TCP keepinit time. > With TCP keepinit set to 25, connect() timesout after about 10 seconds, > while with TCP keepinit set to 75, connect() times out after about 37 seconds. > So it appears the keepinit time is being divided by some value in the range > 2.0 - 2.5 to obtain the actual timeout. All the TCP timers are in terms of PR_SLOWHZ, a kernel-wide constant which is generally 2. (This is noted near the top of /sys/netinet/tcp_timer.h.) That is because all TCP timeouts (except delayed acks) are handled by tcp_timer.c:tcp_slowtimo(), which is called PR_SLOWHZ times per second. Cheers, joelh -- Joel Ray Holveck - joelh@gnu.org Fourth law of programming: Anything that can go wrong wi sendmail: segmentation violation - core dumped To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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