[PATCH v2] mempool: fix get objects from mempool with cache

[Aaron Conole]

Morten Brørup <mb at smartsharesystems.com> writes:

> @Aaron, do you have any insights or comments to my curiosity below?

Sorry, the perf tests from Feb to Oct should *generally* be comparable
but keep in mind that they are based on different baseline versions of
DPDK.  Also, the perf tests are done as thresholds rather than hard
limits (because there can be some minor variations run to run, iirc).

>> From: Andrew Rybchenko [mailto:andrew.rybchenko at oktetlabs.ru]
>> Sent: Tuesday, 4 October 2022 14.58
>> 
>> Hi Morten,
>> 
>> In general I agree that the fix is required.
>> In sent v3 I'm trying to make it a bit better from my point of
>> view. See few notes below.
>
> I stand by my review and accept of v3 - this message is not intended to change that! I'm just curious...
>
> I wonder how accurate the automated performance tests ([v2], [v3])
> are, and if they are comparable between February and October?
>
> [v2]: http://mails.dpdk.org/archives/test-report/2022-February/256462.html
> [v3]: http://mails.dpdk.org/archives/test-report/2022-October/311526.html
>
>
> Ubuntu 20.04
> Kernel: 4.15.0-generic
> Compiler: gcc 7.4
> NIC: Intel Corporation Ethernet Converged Network Adapter XL710-QDA2 40000 Mbps
> Target: x86_64-native-linuxapp-gcc
> Fail/Total: 0/4
>
> Detail performance results:
> ** V2 **:
> +----------+-------------+---------+------------+------------------------------+
> | num_cpus | num_threads | txd/rxd | frame_size |  throughput difference from  |
> |          |             |         |            |           expected           |
> +==========+=============+=========+============+==============================+
> | 1        | 2           | 512     | 64         | 0.5%                         |
> +----------+-------------+---------+------------+------------------------------+
> | 1        | 2           | 2048    | 64         | -1.5%                        |
> +----------+-------------+---------+------------+------------------------------+
> | 1        | 1           | 512     | 64         | 4.3%                         |
> +----------+-------------+---------+------------+------------------------------+
> | 1        | 1           | 2048    | 64         | 10.9%                        |
> +----------+-------------+---------+------------+------------------------------+
>
> ** V3 **:
> +----------+-------------+---------+------------+------------------------------+
> | num_cpus | num_threads | txd/rxd | frame_size |  throughput difference from  |
> |          |             |         |            |           expected           |
> +==========+=============+=========+============+==============================+
> | 1        | 2           | 512     | 64         | -0.7%                        |
> +----------+-------------+---------+------------+------------------------------+
> | 1        | 2           | 2048    | 64         | -2.3%                        |
> +----------+-------------+---------+------------+------------------------------+
> | 1        | 1           | 512     | 64         | 0.5%                         |
> +----------+-------------+---------+------------+------------------------------+
> | 1        | 1           | 2048    | 64         | 7.9%                         |
> +----------+-------------+---------+------------+------------------------------+