[Info-vax] Linux 40 GbE and 100 GbE NIC Performance

[Jan-Erik Soderholm]

terry+googleblog at tmk.com skrev den 2015-01-28 04:11:
> On Tuesday, January 27, 2015 at 10:27:39 AM UTC-5, Bill Gunshannon
> wrote:
>> The only thing that still gets me is I don't think any current machine
>> has an internal bus speed as fast as these network speeds so how to
>> they fill the pipe?
>
> Even 10GbE is often used just as a top-of-rack to core link, not as a
> host-to-switch link. Though that is changing and you can now get 10GbE
> switches for under $100 per (copper) port.
>
> Inside smaller switches, the switching is frequently done on one chip.
> Larger switches link these chips via a number of different methods. So
> switches aren't internally constrained by standard bus speeds.
>
> Getting back to your question, PCI Express 3.x provides more than
> 7.75Gbit/sec per lane (the actual speed is 8 gigatransfers per second,
> but that has some overhead). Multiple lanes are used to connect the
> expansion card to the CPU.
>
> Looking at the 10GbE card I use, the Intel X540-T1, it is PCI Express
> 2.1 compliant and has a useful data rate of 4Gbit/sec per lane. It is an
> 8-lane card, so has the theoretical ability to move 32Gbit/sec. [The
> reason it is an 8-lane card is that the X540-T2 uses the same PCB but
> has 2 ports, otherwise a 4-lane card would do fine for the single
> port.]
>
> Extrapolating to a 16-lane PCI Express 3.x card, the bus offers
> 126Gbit/sec, so it should work for single-port 100GbE cards. By the time
> such cards are common, we should have PCI Express 4.0, which doubles
> speed to 16 gigatransfers per second.
>

But are those top-speeds or sustained speeds? Can the rest of the
system handle that load in a sustained way?

In aprox one second you have filled up 8 GB memory (using 100 GbE)
and then you have to do something with the data also.