[dpdk-dev] [RFC PATCH 0/6] mempool: add bucket mempool driver

Olivier MATZ olivier.matz at 6wind.com
Thu Dec 14 14:36:00 CET 2017

Hi Andrew,

Please find some comments about this patchset below.
I'll also send some comments as replies to the specific patch.

On Fri, Nov 24, 2017 at 04:06:25PM +0000, Andrew Rybchenko wrote:
> The patch series adds bucket mempool driver which allows to allocate
> (both physically and virtually) contiguous blocks of objects and adds
> mempool API to do it. It is still capable to provide separate objects,
> but it is definitely more heavy-weight than ring/stack drivers.
> The target usecase is dequeue in blocks and enqueue separate objects
> back (which are collected in buckets to be dequeued). So, the memory
> pool with bucket driver is created by an application and provided to
> networking PMD receive queue. The choice of bucket driver is done using
> rte_eth_dev_pool_ops_supported(). A PMD that relies upon contiguous
> block allocation should report the bucket driver as the only supported
> and preferred one.

So, you are planning to use this driver for a future/existing PMD?

Do you have numbers about the performance gain, in which conditions,
etc... ? And are there conditions where there is a performance loss ?

> The number of objects in the contiguous block is a function of bucket
> memory size (.config option) and total element size.

The size of the bucket memory is hardcoded to 32KB.
Why this value ?
Won't that be an issue if the user wants to use larger objects?

> As I understand it breaks ABI so it requires 3 acks in accordance with
> policy, deprecation notice and mempool shared library version bump.
> If there is a way to avoid ABI breakage, please, let us know.

If my understanding is correct, the ABI breakage is caused by the
addition of the new block dequeue operation, right?


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