Date: Sun, 6 Nov 2011 15:40:54 -0800 From: YongHyeon PYUN <pyunyh@gmail.com> To: Michael =?iso-8859-1?B?TGHf?= <bevan@bi-co.net> Cc: freebsd-net@freebsd.org Subject: Re: Gigabit Ethernet performance with Realtek 8111E Message-ID: <20111106234054.GB1906@michelle.cdnetworks.com> In-Reply-To: <1320494003.19667.41.camel@bevan-pc.fritz.box> References: <1320494003.19667.41.camel@bevan-pc.fritz.box>
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On Sat, Nov 05, 2011 at 12:53:23PM +0100, Michael La?? wrote: > Hi! > > I've got a small NAS with Intel D525MW (Atom) board inside using FreeBSD > 9.0-RC1 as operating system. It has an onboard Realtek 8111E ethernet > adapter. I'm experiencing heavy performance problems when transfering > files from a specific PC in my network to that NAS. I did the following > tests by transfering large amount of data between the diferrent machines > (using dd and nc): > > NAS -> Linux1: ~ 400Mbit/s > NAS -> Linux2: ~ 400Mbit/s > Linux1 -> NAS: heavy fluctuation, between 700Mbit/s and 0bit/s > Linux2 -> NAS: ~ 400Mbit/s > Linux1 -> Linux2: ~ 400Mbit/s > Linux2 -> Linux1: ~ 400Mbit/s > > As you can see everythink works fine except for transfering data from > Linux1 to that NAS box. The following graph shows the problem: > http://dl.dropbox.com/u/25455527/network-problems.png > > While the transfer rate drops to zero the NAS also has a very bad ping > up to one second. Ping of Linux1 is perfectly fine during these outages. > > I also had a quick look on the data stream with wireshark on Linux1 and > it shows a lot of TCP Dup ACK (up to 263 Dup ACKs created by NAS for one > frame). > > What can be eliminated as a cause is: > - Switch (I tried connecting Linux1 and NAS directly) > - Cable (I changed that a few times) > - Harddisk I/O (I'm only writing from /dev/zero to /dev/null) > > The sevirity of that problem varies from one minute to another but can > always be reproduced with a few tries. > > When limiting either NAS or Linux1 to 100Mbit I'm getting a steady > transfer rate of about 90Mbit/s. Some revisions of RealTek controller have FIFO overrun issue but I'm not sure whether you're seeing the issue. Try enabling flow control and see whether that makes any difference. You can enable it by issuing 'ifconfig re0 media flow'. > When decreasing the MTU on NAS to 1200 the problem seems to disappear, > getting a transfer rate of about 160Mbit/s. > > ifconfig re0: > > re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 > > options=388b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWCSUM,WOL_UCAST,WOL_MCAST,WOL_MAGIC> > > ether 38:60:77:3e:af:a5 > > inet 192.168.178.54 netmask 0xffffff00 broadcast 192.168.178.255 > > nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> > > media: Ethernet autoselect (1000baseT <full-duplex>) > > status: active > > pciconf -lv: > > re0@pci0:1:0:0: class=0x020000 card=0xd6258086 chip=0x816810ec rev=0x06 hdr=0x00 > > vendor = 'Realtek Semiconductor Co., Ltd.' > > device = 'RTL8111/8168B PCI Express Gigabit Ethernet controller' > > class = network > > subclass = ethernet > Show me the dmesg output. RealTek uses the same device PCI ids so it's impossible to know which controller you have from the pciconf(8) output. > Because Linux1 seems to be involved in that problem: It's running Linux > 3.0 and it has an "Atheros Communications AR8121/AR8113/AR8114" onboard. > > Does anyone have an idea what could be the problem here? Decreasing the > MTU is some kind of solution but the performance is still not optimal > and a MTU of 1500 should be no problem. > > Greetings, > Michael Laß
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