[dpdk-users] how can i know the reason why the rx_nombuf couner increase?

[dpdk-users] how can i know the reason why the rx_nombuf couner increase?

[平岡 冠二]

Hi All,

This is my first post here. I've an issue, and I would like your help.

HW Environment:
 HP DL360 Gen10 (Xeon Silver 4208 @ 2.1GHz)
 HPE Ethernet 10Gb 2Port NIC 562T (Intel X550T, driver=5.1.0-k-rh7.6, firmware=10.51.3)

SW Environment:
 DPDK 20.08
 Red Hat Enterprise Linux Server release 7.6 (Maipo)
 Number of mbuf is 1024 * 1024 (plenty!)

I create the packet capture with DPDK 20.08 and received 1.2Gbps(1Mfps) packets on my 
server described above, but, rarely(about once per 100 hours) encountered the packet loss
problem.

To find the reason, I use the rte_eth_stats_get() and found imissed and rx_nombuf counter 
was increased when packet loss was happened.

Is this means that the CPU power was insufficient? or my application rarely slow down? or
none of them?  Does anyone know how can I know that?



on a side note...

When I wrote the captured packet to SSD drive, rarely packet loss was happen, but, 
when I wrote them to SAS HDD drive (it is slower than SSD) the packet loss was not 
occurred(at least one week). it was very mysterious...

Best regards.

Re: [dpdk-users] how can i know the reason why the rx_nombuf couner increase?

[Stephen Hemminger]

On Tue, 8 Sep 2020 07:40:58 +0000
"平岡 冠二" <hiraoka737@oki.com> wrote:

> Hi All,
> 
> This is my first post here. I've an issue, and I would like your help.
> 
> HW Environment:
>  HP DL360 Gen10 (Xeon Silver 4208 @ 2.1GHz)
>  HPE Ethernet 10Gb 2Port NIC 562T (Intel X550T, driver=5.1.0-k-rh7.6, firmware=10.51.3)
> 
> SW Environment:
>  DPDK 20.08
>  Red Hat Enterprise Linux Server release 7.6 (Maipo)
>  Number of mbuf is 1024 * 1024 (plenty!)
> 
> I create the packet capture with DPDK 20.08 and received 1.2Gbps(1Mfps) packets on my 
> server described above, but, rarely(about once per 100 hours) encountered the packet loss
> problem.
> 
> To find the reason, I use the rte_eth_stats_get() and found imissed and rx_nombuf counter 
> was increased when packet loss was happened.
> 
> Is this means that the CPU power was insufficient? or my application rarely slow down? or
> none of them?  Does anyone know how can I know that?

The counter imissed means the application can not keep up with the packet rate.
The counter rx_nombuf means the mbuf pool was not big enough (or your application is
leaking mbufs).

> on a side note...
> 
> When I wrote the captured packet to SSD drive, rarely packet loss was happen, but, 
> when I wrote them to SAS HDD drive (it is slower than SSD) the packet loss was not 
> occurred(at least one week). it was very mysterious...

Not at all surprising, packet capture is limited by speed of writing to file.