Date: Wed, 6 Sep 2006 09:16:03 -0500 (CDT) From: Mike Silbersack <silby@silby.com> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/netinet in_pcb.c tcp_subr.c tcp_timer.c tcp_var.h Message-ID: <20060906091204.B6691@odysseus.silby.com> In-Reply-To: <200609061356.k86DuZ0w016069@repoman.freebsd.org>
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On Wed, 6 Sep 2006, Gleb Smirnoff wrote: > glebius 2006-09-06 13:56:35 UTC > > FreeBSD src repository > > Modified files: > sys/netinet in_pcb.c tcp_subr.c tcp_timer.c tcp_var.h > Log: > o Backout rev. 1.125 of in_pcb.c. It appeared to behave extremely > bad under high load. For example with 40k sockets and 25k tcptw > entries, connect() syscall can run for seconds. Debugging showed > that it iterates the cycle millions times and purges thousands of > tcptw entries at a time. > Besides practical unusability this change is architecturally > wrong. First, in_pcblookup_local() is used in connect() and bind() > syscalls. No stale entries purging shouldn't be done here. Second, > it is a layering violation. So you're returning to the behavior where the system chokes and stops all outbound TCP connections because everything is in the timewait state? There has to be a way to fix the problem without removing this heuristic entirely. How did you run your tests? > o Return back the tcptw purging cycle to tcp_timer_2msl_tw(), > that was removed in rev. 1.78 by rwatson. The commit log of this > revision tells nothing about the reason cycle was removed. Now > we need this cycle, since major cleaner of stale tcptw structures > is removed. Looks good, this is probably the reason for the code in in_pcb behaving so poorly. Did you test just this change alone to see if it solved the problem that you were seeing? Mike "Silby" Silbersackhome | help
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