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From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
To: olivier.matz@6wind.com, konstantin.ananyev@intel.com
Cc: honnappa.nagarahalli@arm.com, gavin.hu@arm.com, dev@dpdk.org, nd@arm.com
Subject: [dpdk-dev] [RFC 0/1] lib/ring: add scatter gather and serial dequeue APIs
Date: Mon, 24 Feb 2020 14:39:30 -0600
Message-ID: <20200224203931.21256-1-honnappa.nagarahalli@arm.com> (raw)

Cover-letter:
RCU defer queue (DQ) APIs place 3 requirements on rte_ring library.
1) Multiple entities are responsible for providing/consuming the
   data in a single element of the DQ. Existing rte_ring APIs
   require an intermediate memcpy in such cases.

   RCU DQ API, rte_rcu_qsbr_dq_enqueue, has to store the token
   (generated by the RCU DQ APIs) and the application data
   (provided by the application) in each element of the DQ.

2) Dequeue the data from DQ only if it meets certain criteria.
   i.e. data needs to be accessed before it can be dequeued.

   RCU DQ API, rte_rcu_qsbr_dq_reclaim, can dequeue the
   element from DQ, only if the token at the head of
   the DQ can be reclaimed. If the token cannot be reclaimed
   the reserved elements need to be discarded.

3) While dequeuing from DQ, only one thread should be allowed
   to reserve elements.

   In order to make rte_rcu_qsbr_dq_reclaim API lock free, the
   'reserve elements in DQ, reclaim the token and revert/commit
   elements in DQ' process needs to be atomic.

The first requirement is satisfied by providing scatter-gather APIs
in rte_ring library. The enqueue/dequeue operations are split
into 3 parts:
a) Move produer's/consumer's head index. i.e. reserve elements in
   the ring and return the pointer in the ring to where the data
   needs to be copied to/from.
b) The application copies the data to/from the pointer.
c) Move producer's/consumer's tail index. i.e. indicate that
   the reserved elements are successfully consumed.
RCU DQ APIs require single element, multiple producer enqueue
operations. 'rte_ring_mp_enqueue_elem_reserve' and
'rte_ring_mp_enqueue_elem_commit' APIs are provided to address
these requirements.

The second and third requirements are satisfied by providing
rte_ring APIs for:
a) Move consumer's head index only if there are no elements
   reserved on the ring.
b) Reset the consumer's head index to its original value.
   i.e. discard the reserved elements.

In this case, RCU DQ APIs require single element, single consumer
dequeue operations. 'rte_ring_dequeue_elem_reserve_serial',
'rte_ring_dequeue_elem_commit' and
'rte_ring_dequeue_elem_revert_serial' APIs are provided to address
these requirements.

Honnappa Nagarahalli (1):
  lib/ring: add scatter gather and serial dequeue APIs

 lib/librte_ring/Makefile           |   1 +
 lib/librte_ring/meson.build        |   1 +
 lib/librte_ring/rte_ring_c11_mem.h |  98 +++++++
 lib/librte_ring/rte_ring_elem_sg.h | 417 +++++++++++++++++++++++++++++
 lib/librte_ring/rte_ring_generic.h |  93 +++++++
 5 files changed, 610 insertions(+)
 create mode 100644 lib/librte_ring/rte_ring_elem_sg.h

-- 
2.17.1


             reply	other threads:[~2020-02-24 20:39 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-24 20:39 Honnappa Nagarahalli [this message]
2020-02-24 20:39 ` [dpdk-dev] [RFC 1/1] " Honnappa Nagarahalli
2020-02-26 20:38   ` Ananyev, Konstantin
2020-02-26 23:21     ` Ananyev, Konstantin
2020-02-28  0:18     ` Honnappa Nagarahalli
2020-03-02 18:20       ` Ananyev, Konstantin
2020-03-04 23:21         ` Honnappa Nagarahalli
2020-03-05 18:26           ` Ananyev, Konstantin
2020-03-25 20:43             ` Honnappa Nagarahalli
2020-10-06 13:29 ` [dpdk-dev] [RFC v2 0/1] lib/ring: add scatter gather APIs Honnappa Nagarahalli
2020-10-06 13:29   ` [dpdk-dev] [RFC v2 1/1] " Honnappa Nagarahalli
2020-10-07  8:27     ` Olivier Matz
2020-10-08 20:44       ` Honnappa Nagarahalli
2020-10-08 20:47         ` Honnappa Nagarahalli
2020-10-09  7:33         ` Olivier Matz
2020-10-09  8:05           ` Ananyev, Konstantin
2020-10-09 22:54             ` Honnappa Nagarahalli
2020-10-12 17:06               ` Ananyev, Konstantin
2020-10-12 16:20     ` Ananyev, Konstantin
2020-10-12 22:31       ` Honnappa Nagarahalli
2020-10-13 11:38         ` Ananyev, Konstantin
2020-10-23  4:43 ` [dpdk-dev] [PATCH v3 0/5] lib/ring: add zero copy APIs Honnappa Nagarahalli
2020-10-23  4:43   ` [dpdk-dev] [PATCH v3 1/5] test/ring: fix the memory dump size Honnappa Nagarahalli
2020-10-23 13:24     ` Ananyev, Konstantin
2020-10-23  4:43   ` [dpdk-dev] [PATCH v3 2/5] lib/ring: add zero copy APIs Honnappa Nagarahalli
2020-10-23 13:59     ` Ananyev, Konstantin
2020-10-24 15:45       ` Honnappa Nagarahalli
2020-10-23  4:43   ` [dpdk-dev] [PATCH v3 3/5] test/ring: move common function to header file Honnappa Nagarahalli
2020-10-23 14:22     ` Ananyev, Konstantin
2020-10-23 23:54       ` Honnappa Nagarahalli
2020-10-24  0:29         ` Stephen Hemminger
2020-10-24  0:31           ` Honnappa Nagarahalli
2020-10-23  4:43   ` [dpdk-dev] [PATCH v3 4/5] test/ring: add functional tests for zero copy APIs Honnappa Nagarahalli
2020-10-23 14:20     ` Ananyev, Konstantin
2020-10-23 22:47       ` Honnappa Nagarahalli
2020-10-23  4:43   ` [dpdk-dev] [PATCH v3 5/5] test/ring: add stress " Honnappa Nagarahalli
2020-10-23 14:11     ` Ananyev, Konstantin
2020-10-24 16:11 ` [dpdk-dev] [PATCH v4 0/8] lib/ring: add " Honnappa Nagarahalli
2020-10-24 16:11   ` [dpdk-dev] [PATCH v4 1/8] " Honnappa Nagarahalli
2020-10-24 16:11   ` [dpdk-dev] [PATCH v4 2/8] test/ring: move common function to header file Honnappa Nagarahalli
2020-10-24 16:11   ` [dpdk-dev] [PATCH v4 3/8] test/ring: add functional tests for zero copy APIs Honnappa Nagarahalli
2020-10-24 16:11   ` [dpdk-dev] [PATCH v4 4/8] test/ring: add stress " Honnappa Nagarahalli
2020-10-24 16:11   ` [dpdk-dev] [PATCH v4 5/8] doc/ring: add zero copy peek APIs Honnappa Nagarahalli
2020-10-24 16:11   ` [dpdk-dev] [PATCH v4 6/8] test/ring: fix the memory dump size Honnappa Nagarahalli
2020-10-24 16:11   ` [dpdk-dev] [PATCH v4 7/8] test/ring: remove unnecessary braces Honnappa Nagarahalli
2020-10-24 16:11   ` [dpdk-dev] [PATCH v4 8/8] test/ring: user uintptr_t instead of unsigned long Honnappa Nagarahalli
2020-10-24 16:18   ` [dpdk-dev] [PATCH v4 0/8] lib/ring: add zero copy APIs Honnappa Nagarahalli
2020-10-25  7:16     ` David Marchand
2020-10-25  8:14       ` Thomas Monjalon
2020-10-25  5:45 ` [dpdk-dev] [PATCH v5 " Honnappa Nagarahalli
2020-10-25  5:45   ` [dpdk-dev] [PATCH v5 1/8] " Honnappa Nagarahalli
2020-10-27 14:11     ` Ananyev, Konstantin
2020-10-25  5:45   ` [dpdk-dev] [PATCH v5 2/8] test/ring: move common function to header file Honnappa Nagarahalli
2020-10-27 13:51     ` Ananyev, Konstantin
2020-10-25  5:45   ` [dpdk-dev] [PATCH v5 3/8] test/ring: add functional tests for zero copy APIs Honnappa Nagarahalli
2020-10-25  5:45   ` [dpdk-dev] [PATCH v5 4/8] test/ring: add stress " Honnappa Nagarahalli
2020-10-25  5:45   ` [dpdk-dev] [PATCH v5 5/8] doc/ring: add zero copy peek APIs Honnappa Nagarahalli
2020-10-27 14:11     ` Ananyev, Konstantin
2020-10-29 10:52     ` David Marchand
2020-10-29 11:28       ` Ananyev, Konstantin
2020-10-29 12:35         ` David Marchand
2020-10-29 17:29           ` Honnappa Nagarahalli
2020-10-25  5:45   ` [dpdk-dev] [PATCH v5 6/8] test/ring: fix the memory dump size Honnappa Nagarahalli
2020-10-25  5:45   ` [dpdk-dev] [PATCH v5 7/8] test/ring: remove unnecessary braces Honnappa Nagarahalli
2020-10-27 14:13     ` Ananyev, Konstantin
2020-10-25  5:45   ` [dpdk-dev] [PATCH v5 8/8] test/ring: user uintptr_t instead of unsigned long Honnappa Nagarahalli
2020-10-27 14:14     ` Ananyev, Konstantin
2020-10-29 13:57   ` [dpdk-dev] [PATCH v5 0/8] lib/ring: add zero copy APIs David Marchand
2020-10-29 22:11     ` Honnappa Nagarahalli

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