On Tue, 15 Oct 2024 14:01:05 +0100
Konstantin Ananyev <konstantin.v.anan...@yandex.ru> wrote:
> From: Konstantin Ananyev <konstantin.anan...@huawei.com>
>
> NOTE UPFRONT: this version is still not ready for merging.
> Missing items:
> - ARM/PPC tests passing
> - PG update
>
> v4 -> v5
> - fix public API/doc comments from Jerin
> - update devtools/build-dict.sh (Stephen)
> - fix MSVC warnings
> - introduce new test-suite for meson (stress) with
> ring_stress_autotest and soring_stress_autotest in it
> - enhance error report in tests
> - reorder some sync code in soring and add extra checks
> (for better debuggability)
>
> v3 -> v4:
> - fix compilation/doxygen complains (attempt #2)
> - updated release notes
>
> v2 -> v3:
> - fix compilation/doxygen complains
> - dropped patch:
> "examples/l3fwd: make ACL work in pipeline and eventdev modes": [2]
> As was mentioned in the patch desctiption it was way too big,
> controversial and incomplete. If the community is ok to introduce
> pipeline model into the l3fwd, then it is propbably worth to be
> a separate patch series.
>
> v1 -> v2:
> - rename 'elmst/objst' to 'meta' (Morten)
> - introduce new data-path APIs set: one with both meta{} and objs[],
> second with just objs[] (Morten)
> - split data-path APIs into burst/bulk flavours (same as rte_ring)
> - added dump function for te_soring and improved dump() for rte_ring.
> - dropped patch:
> " ring: minimize reads of the counterpart cache-line"
> - no performance gain observed
> - actually it does change behavior of conventional rte_ring
> enqueue/dequeue APIs -
> it could return available/free less then actually exist in the ring.
> As in some other libs we reliy on that information - it will
> introduce problems.
>
> The main aim of these series is to extend ring library with
> new API that allows user to create/use Staged-Ordered-Ring (SORING)
> abstraction. In addition to that there are few other patches that serve
> different purposes:
> - first two patches are just code reordering to de-duplicate
> and generalize existing rte_ring code.
> - patch #3 extends rte_ring_dump() to correctly print head/tail metadata
> for different sync modes.
> - next two patches introduce SORING API into the ring library and
> provide UT for it.
>
> SORING overview
> ===============
> Staged-Ordered-Ring (SORING) provides a SW abstraction for 'ordered' queues
> with multiple processing 'stages'. It is based on conventional DPDK
> rte_ring, re-uses many of its concepts, and even substantial part of
> its code.
> It can be viewed as an 'extension' of rte_ring functionality.
> In particular, main SORING properties:
> - circular ring buffer with fixed size objects
> - producer, consumer plus multiple processing stages in between.
> - allows to split objects processing into multiple stages.
> - objects remain in the same ring while moving from one stage to the other,
> initial order is preserved, no extra copying needed.
> - preserves the ingress order of objects within the queue across multiple
> stages
> - each stage (and producer/consumer) can be served by single and/or
> multiple threads.
>
> - number of stages, size and number of objects in the ring are
> configurable at ring initialization time.
>
> Data-path API provides four main operations:
> - enqueue/dequeue works in the same manner as for conventional rte_ring,
> all rte_ring synchronization types are supported.
> - acquire/release - for each stage there is an acquire (start) and
> release (finish) operation. After some objects are 'acquired' -
> given thread can safely assume that it has exclusive ownership of
> these objects till it will invoke 'release' for them.
> After 'release', objects can be 'acquired' by next stage and/or dequeued
> by the consumer (in case of last stage).
>
> Expected use-case: applications that uses pipeline model
> (probably with multiple stages) for packet processing, when preserving
> incoming packet order is important.
>
> The concept of ‘ring with stages’ is similar to DPDK OPDL eventdev PMD [1],
> but the internals are different.
> In particular, SORING maintains internal array of 'states' for each element
> in the ring that is shared by all threads/processes that access the ring.
> That allows 'release' to avoid excessive waits on the tail value and helps
> to improve performancei and scalability.
> In terms of performance, with our measurements rte_soring and
> conventional rte_ring provide nearly identical numbers.
> As an example, on our SUT: Intel ICX CPU @ 2.00GHz,
> l3fwd (--lookup=acl) in pipeline mode [2] both
> rte_ring and rte_soring reach ~20Mpps for single I/O lcore and same
> number of worker lcores.
>
> [1]
> https://www.dpdk.org/wp-content/uploads/sites/35/2018/06/DPDK-China2017-Ma-OPDL.pdf
> [2]
> https://patchwork.dpdk.org/project/dpdk/patch/20240906131348.804-7-konstantin.v.anan...@yandex.ru/
Also needs its own page in the programmers guide (like ring and eventdev) you
could probably use
a variant of the text in this commit message.
