Date: Sun, 04 Oct 2009 19:55:57 +0500 From: rihad <rihad@mail.ru> To: Luigi Rizzo <rizzo@iet.unipi.it> Cc: freebsd-net@freebsd.org Subject: Re: dummynet dropping too many packets Message-ID: <4AC8B77D.6070703@mail.ru> In-Reply-To: <20091004144909.GA42503@onelab2.iet.unipi.it> References: <4AC8A76B.3050502@mail.ru> <20091004144909.GA42503@onelab2.iet.unipi.it>
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Luigi Rizzo wrote: > On Sun, Oct 04, 2009 at 06:47:23PM +0500, rihad wrote: >> Hi, we have around 500-600 mbit/s traffic flowing through a 7.1R Dell >> PowerEdge w/ 2 GigE bce cards. There are currently around 4 thousand ISP >> users online limited by dummynet pipes of various speeds. According to >> netstat -s output around 500-1000 packets are being dropped every second >> (this accounts for wasting around 7-12 mbit/s worth of traffic according >> to systat -ifstat): > > At those speeds you might be hitting various limits with your > config (e.g. 50k nmbclusters is probably way too small for > 4k users -- means you have an average of 10-15 buffers per user; > the queue size of 350kbytes = 2.6Mbits means 2.6 seconds of buffering, > which is quite high besides the fact that in order to scale to 4k users > you would need over 1GB of kernel memory just for the buffers). top output: Mem: 2037M Active, 1248M Inact, 450M Wired, 184M Cache, 214M Buf, 17M Free I guess we're quite far from reaching 1GB of kernel memory.
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