Sub par performance with Intel NIC (82541PI)

[robdeep]

I'm taking CyberJocks advice; new thread!

So I've now got a 9.1 .1 FreeNas system with the following; Intel core i5 2500k, 16gb of ram, 4, 3tb WD Red drives and an Intel PCI nic (Chip 82541PI). My iperf results are less than ideal, ~750Mbps. I've made some adjustments, but can't seem to get past that speed. I've read that speed is probably the top end for a RealTek nic, but Intel can do more.

Meanwhile on the same network switch, I can send 958Mbps from a bloody Macbook Air to my PC (Marvel Nic) all day. I've also tried tried some basic physical changes, like patch cables, but I don't think they have any effect in this case.

I'm thinking about trying another NIC after reading this thread, which had no resolution.
http://freebsd.1045724.n5.nabble.com/em0-performance-subpar-td4345922.html

I appreciate any feedback.

 

[cyberjock]

Ah, you are using PCI. PCI is a bottleneck for Gb. You very likely need to go with PCIe NIC if you want better performance. PCI is a bus architecture, so any other PCI devices will compete for total throughput. In theory, if it is the only device on your PCI bus, you shoudn't be limited. But more often than not other devices on the motherboard will be connected via PCI. And if your SATA/RAID controller is on PCI, then you are just flat out screwed. Performance will always suck as you'll always be doing network transfers and disk accesses at the same time, and both will compete.

Not sure if you are using jumbo frames like the thread you linked, but you should not be using them at this time. They often add more complexity for troubleshooting.

 

[joeschmuck]

Do you have the "enable autotune" checked under advanced settings? Fi not then this will help out since you have 16GB of RAM but it may or maynot help for the speed issue. Also when I was using iperf the platform I was running it on made a difference, not saying this is your problem if you're able to get it to work on other machines as you indicated above. What MB do you have and if it has an onboard NIC, what were the results using that one? And the RealTek vs. Intel is true but RealTek should work fine because you have a fast CPU but Intel does squeeze a little more out. In fact, list all your system specs because you are letting us make assumptions that you have adequate equipment and we might see something obvious that you could fix.

 

[robdeep]

Thanks for the replies. I do have auto tune enabled.

The motherboard is a Gigabyte P55M-UD2. It has a PCI-E and regular 32 bit PCI bus, which is what I have the Intel NIC on. The hard drives are connected to the built in SATA2 controller on the board. So even if it's shared with the PCI bus, I should still have a theoretical 1064MB/second on that bus, and there isn't much competition on the system for PCI bandwidth when I've conducted my iperf tests.

I'm not using Jumbo frames.

I'm open to getting a PCI-E card if that will do it. Would this be a good inexpensive option? Intel CT PCI-E Adapter EXPI9301CTBLK

 

[robdeep]

Actually, I think I'm wrong on that PCI bus figure. It's a lot less isn't it :P Maybe 266.7 MB/s?

 

[cyberjock]

Nope. It's even lower than that. 133MB/sec for all devices combined. PCI is just not recommended at all where performance matters. Once you hit around 80% of PCI's max you start having performance issues because that 133MB/sec is theoretical. PCI still has to talk to other devices(even ones that are idle) to ensure they don't need to send/receive anything either.

 

[robdeep]

I just threw a Intel EXPI9301CT nic in there, and now I'm getting 959Mbps with iperf. Thanks

 

[joeschmuck]

Glad you figured that out.

Your MB uses PCIe for the SATA and RealTek interfaces, look at your users manual page 8. I'm curious what you would get on iperf if using the RealTek. But I do agree, the Intel board will likely get better performance.

 

[cyberjock]

You know.... this makes me wonder if many of the onboard Realteks that underperform are actually attached as a PCI device. Hmm......

 

[robdeep]

Thanks for the feedback guys. The attention to this forum is quite good, especially for an open product like this.