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10 Tips For Boosting Network Performance
snydeq writes "InfoWorld's Paul Venezia and Matt Prigge provide hands-on insights for increasing the efficiency of your organization's network. From losing the leased lines, to building a monster IT test lab on the cheap, to knowing how best to accelerate backups, each tip targets a typical, often overlooked IT bottleneck."
Interrupt Moderation = Disable
Here's a real tip, disable Interrupt Moderation on your Network Adapter Cards to achieve greater bandwidth, as much as 100%+, and lower latency (the two measures of network performance) at the expense of processor utilization due to more hardware interrupts that have to be handled.
Instructions: In Windows open up Control Panel, Network and Sharing Center, click on Change Adapter Settings, open Properties on your Local Area Connection (sometimes #2, #3, or something if you have more network cards), click on the Configure button, then the Advanced tab, select Interrupt Moderation, change the value to Disabled, while there look for any settings with the word Offload and enable them all, and then click the OK button to make the changes. This will restart your network card driver and make the settings effective.
Most network cards from popular manufacturers such as Intel, Broadcom, Realtek, etc. hold network packets in a buffer until enough time goes by before raising a hardware interrupt and telling the processor, operating system, and network driver that there are packets waiting to be serviced. By disabling Interrupt Moderation you instruct the network driver and card to raise the interrupt every single time a packet comes in, thus making your processor service the network card much faster thus decreasing latency on the packets held in the buffer and also increasing bandwidth by allowing more packets to flow through faster. This increases your processor utilization by a significant amount 10-30% but if you have a recent dual, quad, hex, octo-core processor and recent network drivers that are multi-threaded with multi-core support and have Receive Side Scaling support then the increased processor utilization is negligible to your computer and if you are running a network server then network performance should be a priority anyway.
I have personally seen and tested corporate and home LAN environments using Fast Ethernet 100 Mbit/s (~11 MByte/s) go from slow 6-7 MByte/s to 10-11 MByte/s throughput, and Gigabit 1,000 Mbit/s (~100 MByte/s) go from ~30 MByte/s to 95-98 MByte/s speeds due to these changes. No other network driver setting had as much performance impact as Interrupt Moderation.
IEEE 802.1AX (aka 802.3ad, Cisco EtherChannel)
For advanced network performance improvement look at link aggregation (channel trunking, link bonding, etc.) using the IEEE 802.1AX (aka 802.3ad, Cisco EtherChannel) protocol support in your Intel and Broadcom network adapters using their Advanced Configuration Utilities on your servers to bundle from 2-8 Ethernet network adapters into one trunk to increase your performance. Just tell your network administrators to enable those features on your ports and find out if they are able to do it if your links are going to the same switch or if they have virtual switching enabled in case your links span switches. Just think about 4 x Gigabit performance if you bundle all 4 NICs on most servers.
NetCPS
You can test your own network performance with this simple but great utility called NetCPS. Just be sure to disable Interrupt Moderation on both of the computers on your LAN that you will be using for the performance testing otherwise you won't be able to achieve these numbers if one of the computers can't handle the data as fast as the other one. Try it with your laptop and desktop for example.
NetCPS - is a handy utility to measure the effective performance on a TCP/IP network.
Just execute "netcps.exe -s" on the listening system and then do "netcps.exe computername " on the other computer to use the utility to test the throughput bandwidth. For Gigabit you can use the "-m1000" switch to increase the transferred amount to 1,000 MBytes instead of the default 100. Below is an example.
Nice informative post, interrupt moderation sure sounds interesting. Link aggregation, however, is not as useful as it sounds for the following reasons:
1. Hardware link aggregation (link aggregation supported in silicon) works by hashing, not by distributing packets evenly across all links that are aggregated. If you can spare some time to ponder about this for a moment, you will be able to see why hashing is used. In real life situations, 4 x 1Gbps links aggregated together never equals 4Gbps throughput.
2. If link aggregation is handled by the software (which is most likely the case if aggregating multiple NICs on a server) then all it really provides is redundancy. It is very difficult for an average server to process 1Gbps of incoming traffic, let alone generate 1Gbps of worths of traffic. Not to mention the read/write speed of the storage device(s) used in the server.
(Unless it's using PCIE SSDs in RAID configuration, which would be very interesting and I am dying to find out the throughput of such a configuration!)
For once I actually know what I am talking about, so maybe I should have created an account before posting this one.