Re: [RFC v2 00/17] mempool: add bucket mempool driver

[Olivier Matz <olivier.matz@6wind.com>]

Hi,

On Tue, Jan 23, 2018 at 01:15:55PM +0000, Andrew Rybchenko wrote:
> The patch series starts from generic enhancements suggested by Olivier.
> Basically it adds driver callbacks to calculate required memory size and
> to populate objects using provided memory area. It allows to remove
> so-called capability flags used before to tell generic code how to
> allocate and slice allocated memory into mempool objects.
> Clean up which removes get_capabilities and register_memory_area is
> not strictly required, but I think right thing to do.
> Existing mempool drivers are updated.
> 
> I've kept rte_mempool_populate_iova_tab() intact since it seems to
> be not directly related XMEM API functions.
> 
> 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 driver will be used by the future Solarflare driver enhancements
> which allow to utilize physical contiguous blocks in the NIC
> hardware/firmware.
> 
> 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.
> 
> Introduction of the contiguous block dequeue operation is proven by
> performance measurements using autotest with minor enhancements:
>  - in the original test bulks are powers of two, which is unacceptable
>    for us, so they are changed to multiple of contig_block_size;
>  - the test code is duplicated to support plain dequeue and
>    dequeue_contig_blocks;
>  - all the extra test variations (with/without cache etc) are eliminated;
>  - a fake read from the dequeued buffer is added (in both cases) to
>    simulate mbufs access.
> 
> start performance test for bucket (without cache)
> mempool_autotest cache=   0 cores= 1 n_get_bulk=  15 n_put_bulk=   1 n_keep=  30 Srate_persec=   111935488
> mempool_autotest cache=   0 cores= 1 n_get_bulk=  15 n_put_bulk=   1 n_keep=  60 Srate_persec=   115290931
> mempool_autotest cache=   0 cores= 1 n_get_bulk=  15 n_put_bulk=  15 n_keep=  30 Srate_persec=   353055539
> mempool_autotest cache=   0 cores= 1 n_get_bulk=  15 n_put_bulk=  15 n_keep=  60 Srate_persec=   353330790
> mempool_autotest cache=   0 cores= 2 n_get_bulk=  15 n_put_bulk=   1 n_keep=  30 Srate_persec=   224657407
> mempool_autotest cache=   0 cores= 2 n_get_bulk=  15 n_put_bulk=   1 n_keep=  60 Srate_persec=   230411468
> mempool_autotest cache=   0 cores= 2 n_get_bulk=  15 n_put_bulk=  15 n_keep=  30 Srate_persec=   706700902
> mempool_autotest cache=   0 cores= 2 n_get_bulk=  15 n_put_bulk=  15 n_keep=  60 Srate_persec=   703673139
> mempool_autotest cache=   0 cores= 4 n_get_bulk=  15 n_put_bulk=   1 n_keep=  30 Srate_persec=   425236887
> mempool_autotest cache=   0 cores= 4 n_get_bulk=  15 n_put_bulk=   1 n_keep=  60 Srate_persec=   437295512
> mempool_autotest cache=   0 cores= 4 n_get_bulk=  15 n_put_bulk=  15 n_keep=  30 Srate_persec=  1343409356
> mempool_autotest cache=   0 cores= 4 n_get_bulk=  15 n_put_bulk=  15 n_keep=  60 Srate_persec=  1336567397
> start performance test for bucket (without cache + contiguous dequeue)
> mempool_autotest cache=   0 cores= 1 n_get_bulk=  15 n_put_bulk=   1 n_keep=  30 Crate_persec=   122945536
> mempool_autotest cache=   0 cores= 1 n_get_bulk=  15 n_put_bulk=   1 n_keep=  60 Crate_persec=   126458265
> mempool_autotest cache=   0 cores= 1 n_get_bulk=  15 n_put_bulk=  15 n_keep=  30 Crate_persec=   374262988
> mempool_autotest cache=   0 cores= 1 n_get_bulk=  15 n_put_bulk=  15 n_keep=  60 Crate_persec=   377316966
> mempool_autotest cache=   0 cores= 2 n_get_bulk=  15 n_put_bulk=   1 n_keep=  30 Crate_persec=   244842496
> mempool_autotest cache=   0 cores= 2 n_get_bulk=  15 n_put_bulk=   1 n_keep=  60 Crate_persec=   251618917
> mempool_autotest cache=   0 cores= 2 n_get_bulk=  15 n_put_bulk=  15 n_keep=  30 Crate_persec=   751226060
> mempool_autotest cache=   0 cores= 2 n_get_bulk=  15 n_put_bulk=  15 n_keep=  60 Crate_persec=   756233010
> mempool_autotest cache=   0 cores= 4 n_get_bulk=  15 n_put_bulk=   1 n_keep=  30 Crate_persec=   462068120
> mempool_autotest cache=   0 cores= 4 n_get_bulk=  15 n_put_bulk=   1 n_keep=  60 Crate_persec=   476997221
> mempool_autotest cache=   0 cores= 4 n_get_bulk=  15 n_put_bulk=  15 n_keep=  30 Crate_persec=  1432171313
> mempool_autotest cache=   0 cores= 4 n_get_bulk=  15 n_put_bulk=  15 n_keep=  60 Crate_persec=  1438829771
> 
> The number of objects in the contiguous block is a function of bucket
> memory size (.config option) and total element size. In the future
> additional API with possibility to pass parameters on mempool allocation
> may be added.
> 
> It breaks ABI since changes rte_mempool_ops. Also it removes
> rte_mempool_ops_register_memory_area() and
> rte_mempool_ops_get_capabilities() since corresponding callbacks are
> removed.
> 
> The target DPDK release is 18.05.
> 
> v2:
>   - add driver ops to calculate required memory size and populate
>     mempool objects, remove extra flags which were required before
>     to control it
>   - transition of octeontx and dpaa drivers to the new callbacks
>   - change info API to get information from driver required to
>     API user to know contiguous block size
>   - remove get_capabilities (not required any more and may be
>     substituted with more in info get API)
>   - remove register_memory_area since it is substituted with
>     populate callback which can do more
>   - use SPDX tags
>   - avoid all objects affinity to single lcore
>   - fix bucket get_count
>   - deprecate XMEM API
>   - avoid introduction of a new function to flush cache
>   - fix NO_CACHE_ALIGN case in bucket mempool
> 
> Andrew Rybchenko (10):
>   mempool: fix phys contig check if populate default skipped
>   mempool: add op to calculate memory size to be allocated
>   mempool/octeontx: add callback to calculate memory size
>   mempool: add op to populate objects using provided memory
>   mempool/octeontx: implement callback to populate objects
>   mempool: remove callback to get capabilities
>   mempool: deprecate xmem functions
>   mempool/octeontx: prepare to remove register memory area op
>   mempool/dpaa: convert to use populate driver op
>   mempool: remove callback to register memory area
> 
> Artem V. Andreev (7):
>   mempool: ensure the mempool is initialized before populating
>   mempool/bucket: implement bucket mempool manager
>   mempool: support flushing the default cache of the mempool
>   mempool: implement abstract mempool info API
>   mempool: support block dequeue operation
>   mempool/bucket: implement block dequeue operation
>   mempool/bucket: do not allow one lcore to grab all buckets
> 
>  MAINTAINERS                                        |   9 +
>  config/common_base                                 |   2 +
>  drivers/mempool/Makefile                           |   1 +
>  drivers/mempool/bucket/Makefile                    |  27 +
>  drivers/mempool/bucket/rte_mempool_bucket.c        | 626 +++++++++++++++++++++
>  .../mempool/bucket/rte_mempool_bucket_version.map  |   4 +
>  drivers/mempool/dpaa/dpaa_mempool.c                |  13 +-
>  drivers/mempool/octeontx/rte_mempool_octeontx.c    |  63 ++-
>  lib/librte_mempool/rte_mempool.c                   | 192 ++++---
>  lib/librte_mempool/rte_mempool.h                   | 366 +++++++++---
>  lib/librte_mempool/rte_mempool_ops.c               |  48 +-
>  lib/librte_mempool/rte_mempool_version.map         |  11 +-
>  mk/rte.app.mk                                      |   1 +
>  13 files changed, 1184 insertions(+), 179 deletions(-)
>  create mode 100644 drivers/mempool/bucket/Makefile
>  create mode 100644 drivers/mempool/bucket/rte_mempool_bucket.c
>  create mode 100644 drivers/mempool/bucket/rte_mempool_bucket_version.map

Globally, the RFC looks fine to me. Thanks for this good work.

I didn't review the mempool/bucket part like I did last time. About the
changes to the mempool API, I think it's a good enhancement: it makes
things more flexible and removes complexity in the common code. Some
points may still need some discussions, for instance how the PMDs and
applications take advantage of block dequeue operations and get_info().

I have some specific comments that are sent directly as replies to the
patches.

Since it changes dpaa and octeontx, having feedback from people from NXP
and Cavium Networks would be good.

Thanks,
Olivier