[dpdk-users] what is the average latency you get for io forwarding from dpdk?

[dpdk-users] what is the average latency you get for io forwarding from dpdk?

[Marco Kwok]

Hello all,

I wonder if anyone could get a relative low latency from dpdk on 1gb link.

When using testpmd, an packet of 150 bytes is sent, packet is received by
the port and loopback to the sender.
I usually could get 50us for io forward. Sometime it can be as fast as 3us.
However it is too slow to be used for switching application.

My test platform is on a intel NUC NUC5I5RYH, which has i5 5250U 1.6GHz,
16GB DDR3 and i218-V network chip. dpdk 16.07.2


I have done the following things try to get a better latency with no luck:
-setup 1G hugepages
-disable cpu frequency scaling to make sure cpu runs at max speed of 2.7GHz
-isolate a cpu core from kernel task scheduler by isolcpus
-setting the burst size of testpmd to 1

Guys, I really want your input. I don't need high throughput but low
latency. Does anyone of you have been able to achieve a lower latency with
dpdk? I don't see the advantage I have taken from dpdk now.

Best,
Mark

Re: [dpdk-users] what is the average latency you get for io forwarding from dpdk?

[dave seddon]

There's an interesting video about speed:
https://youtu.be/ne3svryuthI

On Jan 17, 2017 12:28 AM, "Marco Kwok" <maruko.kwok@gmail.com> wrote:

> Hello all,
>
> I wonder if anyone could get a relative low latency from dpdk on 1gb link.
>
> When using testpmd, an packet of 150 bytes is sent, packet is received by
> the port and loopback to the sender.
> I usually could get 50us for io forward. Sometime it can be as fast as 3us.
> However it is too slow to be used for switching application.
>
> My test platform is on a intel NUC NUC5I5RYH, which has i5 5250U 1.6GHz,
> 16GB DDR3 and i218-V network chip. dpdk 16.07.2
>
>
> I have done the following things try to get a better latency with no luck:
> -setup 1G hugepages
> -disable cpu frequency scaling to make sure cpu runs at max speed of 2.7GHz
> -isolate a cpu core from kernel task scheduler by isolcpus
> -setting the burst size of testpmd to 1
>
> Guys, I really want your input. I don't need high throughput but low
> latency. Does anyone of you have been able to achieve a lower latency with
> dpdk? I don't see the advantage I have taken from dpdk now.
>
> Best,
> Mark
>

Re: [dpdk-users] what is the average latency you get for io forwarding from dpdk?

[Pavel Shirshov]

Hi Maruko,

I'd say that dpdk is not about minimal latency, but about maximum
flexibility and development speed.
dpdk is not ASIC.
ASIC, FPGA, anything not soft related will give you better latency time.
So if you are looking for minimal and predictable latency I suspect
you need to think about other options.


On Tue, Jan 17, 2017 at 12:28 AM, Marco Kwok <maruko.kwok@gmail.com> wrote:
> Hello all,
>
> I wonder if anyone could get a relative low latency from dpdk on 1gb link.
>
> When using testpmd, an packet of 150 bytes is sent, packet is received by
> the port and loopback to the sender.
> I usually could get 50us for io forward. Sometime it can be as fast as 3us.
> However it is too slow to be used for switching application.
>
> My test platform is on a intel NUC NUC5I5RYH, which has i5 5250U 1.6GHz,
> 16GB DDR3 and i218-V network chip. dpdk 16.07.2
>
>
> I have done the following things try to get a better latency with no luck:
> -setup 1G hugepages
> -disable cpu frequency scaling to make sure cpu runs at max speed of 2.7GHz
> -isolate a cpu core from kernel task scheduler by isolcpus
> -setting the burst size of testpmd to 1
>
> Guys, I really want your input. I don't need high throughput but low
> latency. Does anyone of you have been able to achieve a lower latency with
> dpdk? I don't see the advantage I have taken from dpdk now.
>
> Best,
> Mark

Re: [dpdk-users] what is the average latency you get for io forwarding from dpdk?

[Stephen Hemminger]

On Tue, 17 Jan 2017 16:28:01 +0800
Marco Kwok <maruko.kwok@gmail.com> wrote:

> My test platform is on a intel NUC NUC5I5RYH, which has i5 5250U 1.6GHz,
> 16GB DDR3 and i218-V network chip. dpdk 16.07.2

You may need a faster cpu, and PCI gen3 support (so that NIC goes direct to CPU cache).
Also i218-V uses E1000 driver which has not been optimized much.

> I have done the following things try to get a better latency with no luck:
> -setup 1G hugepages
> -disable cpu frequency scaling to make sure cpu runs at max speed of 2.7GHz
> -isolate a cpu core from kernel task scheduler by isolcpus
> -setting the burst size of testpmd to 1

Disable hyper-threading
Set burst size to 32, some drivers optimize for this.
Use different prefetch values