[dpdk-dev] [PATCH] mbuf: replace c memcpy code semantics with optimized rte_memcpy

[Hunt, David]

On 5/27/2016 11:24 AM, Hunt, David wrote:
>
>
> On 5/24/2016 4:17 PM, Jerin Jacob wrote:
>> On Tue, May 24, 2016 at 04:59:47PM +0200, Olivier Matz wrote:
>>
>>> Are you seeing some performance improvement by using rte_memcpy()?
>> Yes, In some case, In default case, It was replaced with memcpy by the
>> compiler itself(gcc 5.3). But when I tried external mempool manager 
>> patch and
>> then performance dropped almost 800Kpps. Debugging further it turns 
>> out that
>> external mempool managers unrelated change was knocking out the memcpy.
>> explicit rte_memcpy brought back 500Kpps. Remaing 300Kpps drop is still
>> unknown(In my test setup, packets are in the local cache, so it must be
>> something do with __mempool_put_bulk text alignment change or similar.
>>
>> Anyone else observed performance drop with external poolmanager?
>>
>> Jerin
>
> Jerin,
>     I'm seeing a 300kpps drop in throughput when I apply this on top 
> of the external
> mempool manager patch. If you're seeing an increase if you apply this 
> patch first, then
> a drop when applying the mempool manager, the two patches must be 
> conflicting in
> some way. We probably need to investigate further.
> Regards,
> Dave.
>

On further investigation, I now have a setup with no performance 
degradation. My previous tests
were accessing the NICS on a different NUMA node. Once I initiated 
testPMD with the correct coremask,
the difference between pre and post rte_memcpy patch is negligible 
(maybe 0.1% drop).

Regards,
Dave.