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I have a HP Touchsmart TM2 2105 laptop, quite recently bought. The NIC is Gigabit speed capable, with a Realtek R8168 chipset.

I installed the drivers from Realtek, it works, ethtools indicates 1000Mpbs. But a simple download test with a Windows PC shows a maximum speed of 130 Mbits. The same test, with the same hardware, but with the laptop under Windows (on another partition) shows approximately 500 Mbps.

I don't know what to do?

The other machine and the switch are gigabit capable, since, the download test with the same machines but under Windows gives approximately 500 Mbps.

I will try MTU and let you know.

If I test under Linux with the command iperf, I get app 650 Mbps!

edit : with MTU= 9000 -> no difference :(

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1) Are you sure the speed you are seeing is 130 megabits per second, and not 130 megabytes per second? A gigabit NIC is going to top out at a little under 130 megabytes per second. 2) I suggest you see if you can turn on jumbo frames (MTU > 1500), and if you can, whether that helps. – Slartibartfast Sep 18 '11 at 22:09
Is the OTHER machine GigaBit capable? Is your router? switch? Unless you're directly connecting the two machines, there's other stops on the cable to consider. But @Slartibartfast has a point, doing the math gives 130MBps (Bytes) theoretical top speed. – lornix Sep 18 '11 at 22:54
Of course, I missed the part about it being same machine, different stats. My mistake. Jumbo frames will likely improve your throughput, as linux doesn't enable them by default, whereas Windows might. – lornix Sep 18 '11 at 23:08
Well, the last time I had this sort of issue on Linux, it had to do with the Ethernet cable connecting the Ubuntu machine to the networking switch/router. I replaced the cable, and it went back to 926Mbits/s. Obviously, you need to have Gigabit cable gear all along the route to the other computer (running iperf, I guess), along with good cables. – Sonny Jan 23 '15 at 18:27
PS: BTW, the max I could push things on the link was about 960Mbits/s using 10 parallel streams of UDP pumping at 125MB/s. I.e., iperf -c <serverIP> -u -P 10 -i 1 -p 5001 -f k -b 125.0M -t 10 -T 1 – Sonny Jan 23 '15 at 18:35

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