Date: Sun, 4 Oct 2009 17:11:17 +0200 From: Luigi Rizzo <rizzo@iet.unipi.it> To: rihad <rihad@mail.ru> Cc: freebsd-net@freebsd.org Subject: Re: dummynet dropping too many packets Message-ID: <20091004151117.GA42877@onelab2.iet.unipi.it> In-Reply-To: <4AC8B77D.6070703@mail.ru> References: <4AC8A76B.3050502@mail.ru> <20091004144909.GA42503@onelab2.iet.unipi.it> <4AC8B77D.6070703@mail.ru>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sun, Oct 04, 2009 at 07:55:57PM +0500, rihad wrote: > 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. of course, you'd have to configure also 500k nmbclusters (and then probably this would not fit)
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20091004151117.GA42877>