Date: Sat, 5 Nov 2011 11:03:50 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: bevan@bi-co.net Cc: freebsd-net@freebsd.org Subject: Re: Gigabit Ethernet performance with Realtek 8111E Message-ID: <1893638131.1215459.1320505430915.JavaMail.root@erie.cs.uoguelph.ca> In-Reply-To: <1320494003.19667.41.camel@bevan-pc.fritz.box>
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bevan wrote: > Hi! >=20 > 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): >=20 > 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 >=20 > 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 >=20 > 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. >=20 > 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). >=20 > 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) >=20 > The sevirity of that problem varies from one minute to another but can > always be reproduced with a few tries. >=20 > When limiting either NAS or Linux1 to 100Mbit I'm getting a steady > transfer rate of about 90Mbit/s. > When decreasing the MTU on NAS to 1200 the problem seems to disappear, > getting a transfer rate of about 160Mbit/s. >=20 > ifconfig re0: > > re0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu > > 1500 > > =09options=3D388b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWCSUM,WOL_UCAST,WOL_MCAS= T,WOL_MAGIC> > > =09ether 38:60:77:3e:af:a5 > > =09inet 192.168.178.54 netmask 0xffffff00 broadcast 192.168.178.255 > > =09nd6 options=3D29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> > > =09media: Ethernet autoselect (1000baseT <full-duplex>) > > =09status: active >=20 try typing: # sysctl dev.re.0.stats=3D1 - this will dump out the stats on the chip if the "Rx missed frames" count is non-zero, you're probably snookered, to put it technically:-) - That's what I get for a re chip is this laptop and I haven't found a way around it. I just live with flakey net performance. rick > pciconf -lv: > > re0@pci0:1:0:0: class=3D0x020000 card=3D0xd6258086 chip=3D0x816810ec > > rev=3D0x06 hdr=3D0x00 > > vendor =3D 'Realtek Semiconductor Co., Ltd.' > > device =3D 'RTL8111/8168B PCI Express Gigabit Ethernet controller' > > class =3D network > > subclass =3D ethernet >=20 > 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. >=20 > 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. >=20 > Greetings, > Michael La=C3=9F >=20 > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
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