DPDK performances surprise

[Antonio Di Bacco]

This tool seems awesome!!! Better than VTUNE?

On Thu, May 19, 2022 at 10:29 AM Kinsella, Ray <ray.kinsella at intel.com>
wrote:

> I’d say that is likely yes.
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> FYI - pcm-memory is very handy tool for looking at memory traffic.
>
> https://github.com/opcm/pcm
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> Thanks,
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> Ray K
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>
> *From:* Sanford, Robert <rsanford at akamai.com>
> *Sent:* Wednesday 18 May 2022 17:53
> *To:* Antonio Di Bacco <a.dibacco.ks at gmail.com>; users at dpdk.org
> *Subject:* Re: DPDK performances surprise
>
>
>
> My guess is that most of the packet data has a short life in the L3 cache
> (before being overwritten by newer packets), but is never flushed to memory.
>
>
>
> *From: *Antonio Di Bacco <a.dibacco.ks at gmail.com>
> *Date: *Wednesday, May 18, 2022 at 12:40 PM
> *To: *"users at dpdk.org" <users at dpdk.org>
> *Subject: *DPDK performances surprise
>
>
>
> I recently read a performance test where l2fwd was able to receive packets
> (8000B) from a 100 Gbps card, swap the L2 addresses and send them back to
> the same port to be received by an ethernet analyzer. The throughput
> achieved was close to 100 Gbps on a XEON machine (Intel(R) Xeon(R) Platinum
> 8176 CPU @ 2.10GHz) . This is the same processor I have and I know that, if
> I try to write around 8000B to the attached DDR4 (2666MT/s) on an allocated
> 1GB hugepage, I get a maximum throughput of around 20GB/s.
>
>
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> Now, a 100 Gbps can generate a flow of around 12 GB/s, these packets have
> to be written to the DDR and then read back to swap L2 addresses and this
> leads to a cumulative bandwidth on the DDR that is around 2x12 GB/s and is
> more than the 20GB/s of available bandwidth on the DDR4.
>
>
>
> How can this be possible ?
>
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