Re: [dpdk-dev] [PATCH 4/4] examples/l3fwd: make data struct to be memory efficient

[Hemant Agrawal <hemant.agrawal@oss.nxp.com>]

On 4/14/2021 12:36 AM, Jerin Jacob wrote:
> On Thu, Mar 18, 2021 at 3:56 PM Ruifeng Wang <ruifeng.wang@arm.com> wrote:
>> There are some holes in data struct lcore_conf. The holes are
>> due to alignment requirement.
>>
>> For struct lcore_rx_queue, there is no need to make every element
>> of this type to be cache line aligned, because the data is not
>> shared between cores.
>>
>> Member len of struct mbuf_table can be moved out. So data can be
>> packed and there will be no need to load an extra cache line when
>> mbuf table is empty.
>>
>> The change showed slight performance improvement on N1SDP platform.
>>
>> Suggested-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
>>
>> Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
> This change alone is OK in the octeontx2 platform.(No difference in performance)
> combining with 3/4 shows some regression. Probably is due to prefetch
> or 128B cache line tuning specifics.

We checked it on Layerscape LS2088A platform. No difference for 1-2 core 
case. However observing ~2% regression for 4-8 cores.

Regards,

Hemant