Date: Fri, 12 Nov 2010 20:44:29 +1100 From: Lawrence Stewart <lstewart@freebsd.org> To: Andre Oppermann <andre@freebsd.org> Cc: freebsd-net@freebsd.org, Igor Sysoev <is@rambler-co.ru>, Maxim Dounin <mdounin@mdounin.ru> Subject: Re: net.inet.tcp.slowstart_flightsize in 8-STABLE Message-ID: <4CDD0C7D.1070102@freebsd.org> In-Reply-To: <4CD64814.2000906@freebsd.org> References: <20100512124702.GJ2679@rambler-co.ru> <20100713140051.GV99657@mdounin.ru> <4C5BCE48.5070504@freebsd.org> <20100913172453.GG99657@mdounin.ru> <20100927081217.GM44164@mdounin.ru> <4CA09987.8020205@freebsd.org> <20101102001134.GP44164@mdounin.ru> <4CD090EF.4020402@freebsd.org> <4CD64814.2000906@freebsd.org>
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On 11/07/10 17:32, Lawrence Stewart wrote: > On 11/03/10 09:30, Andre Oppermann wrote: >> On 02.11.2010 01:11, Maxim Dounin wrote: >>> Hello! >>> >>> On Mon, Sep 27, 2010 at 03:17:59PM +0200, Andre Oppermann wrote: >>> >>>> On 27.09.2010 10:12, Maxim Dounin wrote: >>>>> Hello! >>>>> >>>>> On Mon, Sep 13, 2010 at 09:24:53PM +0400, Maxim Dounin wrote: >>>>> >>>>> [...] >>>>> >>>>>> Andre, could you please take a look at one more patch as well? >>>>>> >>>>>> Igor reported that it still sees 100ms delays with rfc3465 turned >>>>>> on, and it turns out to be similar issue (setting cwnd to 1*MSS) >>>>>> for hosts found in hostcache. >>>>>> >>>>>> The problem with setting cwnd from hostcache was already reported >>>>>> here: >>>>>> >>>>>> http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/92690 >>>>>> http://lists.freebsd.org/pipermail/freebsd-net/2007-July/014780.html >>>>>> >>>>>> As using larger cwnd from hostcache may cause problems on >>>>>> congested links (see second thread) I changed code to only use >>>>>> cached cwnd as an upper bound for cwnd (instead of fixing current >>>>>> code). This is also in-line with what we do on connection >>>>>> restarts. >>>>>> >>>>>> We may later consider re-adding usage of larger cwnd from >>>>>> hostcache. But I believe it should be done carefully and >>>>>> probably behind sysctl, off by default. >>>>> >>>>> Ping. >>>> >>>> Thanks for the reminder. I'll disable priming CWND from hostcache. >>> >>> Ping again. >>> >>> I would like to see the patch in question[1] committed and MFC'ed >>> somewhere before 8.2. >>> >>> Andre, if you are just too busy to do it yourself - please say so, >>> I'll ask somebody else to commit it. >> >> Thanks for the reminder. After EuroBSDCon Developer Summit I was >> busy with other work and most of my tcp work was stalled due to >> review bandwidth issues. > > Sorry for the review bandwidth issues. I'm only just managing to keep my > head above water at the moment and have had to reduce much of my FreeBSD > work to a trickle. > >> Lawrence, could you please spare a few seconds and take a quick look >> at the attached patch? > > The patch looks fine, please commit. I hope to give the hostcache some > TLC at some point, but in the meantime it's fine to ignore cached cwnd. FYI Andre, this patch got rolled into r215166 because I had to move all the code around which the patch was based on. Is that going to cause any issues here? I should have checked prior to committing but completely forgot I had pulled the patch into my dev tree before creating the mod CC patch. Cheers, Lawrence
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