Re: IP performance question
On Tue, May 26, 2015 at 12:57:52PM +0200, Petter Adsen wrote:
>
> > > > > > > I've been trying to improve NFS performance at home, and in
> > > > > > > that process i ran iperf to get an overview of general
> > > > > > > network performance. I have two Jessie hosts connected to a
> > > > > > > dumb switch with Cat-5e. One host uses a Realtek RTL8169
> > > > > > > PCI controller, and the other has an Intel 82583V on the
> > > > > > > motherboard.
> > > > > > >
> > > > > > > iperf maxes out at about 725Mbps. At first I thought maybe
> > > > > > > the switch could be at fault, it's a really cheap one, so I
> > > > > > > connected both hosts to my router instead. Didn't change
> > > > > > > anything, and it had no significant impact on the load on
> > > > > > > the router. I can't try to run iperf on the router
> > > > > > > (OpenWRT), though, as it maxes out the CPU.
> > > > > > >
> > > > > > > Should I be getting more than 725Mbps in the real world?
> > > > > >
> > > > > > A quick test in my current environment shows this:
> > > > > >
> > > > > > [ ID] Interval Transfer Bandwidth
> > > > > > [ 3] 0.0-10.0 sec 1.10 GBytes 941 Mbits/sec
> > > > > >
> > > > > > Two hosts, connected via Cisco 8-port unmanaged switch,
> > > > > > Realtek 8168e on one host, Atheros Attansic L1 on another.
> > > > > >
> > > > > > On the other hand, the same test, Realtek 8139e on one side,
> > > > > > but with lowly Marvell ARM SOC on the other side shows this:
> > > > > >
> > > > > > [ ID] Interval Transfer Bandwidth
> > > > > > [ 3] 0.0-10.0 sec 534 MBytes 448 Mbits/sec
> > > > > >
> > > > > > So - you can, definitely, and yes, it depends.
> > > > >
> > > > > That last one, would that be limited because of CPU power?
> > > >
> > > > That too. You cannot extract that much juice from a single-core
> > > > ARM5. Another possibility is that Marvell is unable to design a
> > > > good chipset even in the case it would be a matter of life and
> > > > death :)
> > >
> > > That might be why I'm not using the Marvell adapter :) I remember
> > > reading somewhere that either Marvell or Realtek were bad, but I
> > > couldn't remember which one, so I kept using the Realtek one since I
> > > had obviously switched for a reason :)
> >
> > Both are actually. Realtek *was* good at least 5 years ago, but since
> > then they managed to introduce multiple chips that are managed by the
> > same r8169 kernel module. Since then it became a matter of luck.
> > Either your NIC works flawlessly without any firmware (mine does), or
> > you're getting all kinds of weird glitches.
>
> The Realtek is not at all new, but I have no idea just how old, as it
> was given to me by a friend. 5 years sounds about right, though. I do
> have the firmware installed, haven't tried without it.
>
> I'm slowly beginning to think about getting another NIC, but what? I've
> heard good things about Intel, and the Intel in the other box is
> behaving well. Are there any specific chipsets to buy or stay away
> from? The one I have is a 82583V.
>
> I haven't bought a separate NIC since the days of the DEC 21140 :)
I'd recommend anything Intel 82576-based. Especially Intel 82576EB.
Server-grade card, multiple ports, goes into PCI-X, sells for about $50
on Ebay near you. Accept no substitutes as anything else is a toy
NIC anyway :)
Reco
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