Date: Tue, 18 Dec 2007 14:49:28 +0300 From: Ruslan Ermilov <ru@FreeBSD.org> To: Peter Wemm <peter@FreeBSD.org> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/netinet tcp_subr.c tcp_timer.h Message-ID: <20071218114928.GC1316@team.vega.ru> In-Reply-To: <20071218033921.56E7D16A5B9@hub.freebsd.org> <200712180339.lBI3dHlU018368@repoman.freebsd.org> References: <200712180339.lBI3dHlU018368@repoman.freebsd.org> <20071218033921.56E7D16A5B9@hub.freebsd.org> <200712180339.lBI3dHlU018368@repoman.freebsd.org>
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Hi, On Tue, Dec 18, 2007 at 03:39:17AM +0000, Peter Wemm wrote: > peter 2007-12-18 03:39:17 UTC > > FreeBSD src repository > > Modified files: (Branch: RELENG_6) > sys/netinet tcp_subr.c tcp_timer.h > Log: > MFC: scale TCPTV_MIN with hz, not a fixed number of ticks. Otherwise > machines with hz=1000 drop connections in a matter of a few seconds on a > fast link (eg: ethernet). With this change, it drops them in the same > time as a machine with hz=100 would. > > Revision Changes Path > 1.228.2.16 +2 -0 src/sys/netinet/tcp_subr.c > 1.27.2.4 +1 -1 src/sys/netinet/tcp_timer.h That explains why I couldn't find a matching code for the following comment in HEAD this morning (just above the changed code): * Minimum retransmit timer is 3 ticks, for algorithmic stability. Please fix. Also, the last sentence in this comment block now looks rotted: * The prior minimum of 1*hz (1 second) badly breaks throughput on any * networks faster then a modem that has minor (e.g. 1%) packet loss. > Index: src/sys/netinet/tcp_timer.h > diff -u src/sys/netinet/tcp_timer.h:1.27.2.3 src/sys/netinet/tcp_timer.h:1.27.2.4 > --- src/sys/netinet/tcp_timer.h:1.27.2.3 Fri Sep 15 09:51:05 2006 > +++ src/sys/netinet/tcp_timer.h Tue Dec 18 03:39:17 2007 > @@ -109,7 +109,7 @@ > * The prior minimum of 1*hz (1 second) badly breaks throughput on any > * networks faster then a modem that has minor (e.g. 1%) packet loss. > */ > -#define TCPTV_MIN ( 3 ) /* minimum allowable value */ > +#define TCPTV_MIN ( hz/33 ) /* minimum allowable value */ > #define TCPTV_CPU_VAR ( hz/5 ) /* cpu variance allowed (200ms) */ > #define TCPTV_REXMTMAX ( 64*hz) /* max allowable REXMT value */ Cheers, -- Ruslan Ermilov ru@FreeBSD.org FreeBSD committer
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