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ring: add zero copy API

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Add zero-copy APIs. These APIs provide the capability to
copy the data to/from the ring memory directly, without
having a temporary copy (for ex: an array of mbufs on
the stack). Use cases that involve copying large amount
of data to/from the ring can benefit from these APIs.

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Dharmik Thakkar <dharmik.thakkar@arm.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
This commit is contained in:
Honnappa Nagarahalli 2020-10-25 00:45:49 -05:00 committed by David Marchand
parent 6c3416659f
commit 47bec9a5ca
5 changed files with 601 additions and 0 deletions
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41
doc/guides/prog_guide/ring_lib.rst
View File

@ -452,6 +452,47 @@ selected. As an example of usage:
Note that between ``_start_`` and ``_finish_`` none other thread can proceed
with enqueue(/dequeue) operation till ``_finish_`` completes.
Ring Peek Zero Copy API
-----------------------
Along with the advantages of the peek APIs, zero copy APIs provide the ability
to copy the data to the ring memory directly without the need for temporary
storage (for ex: array of mbufs on the stack).
These APIs make it possible to split public enqueue/dequeue API into 3 phases:
* enqueue/dequeue start
* copy data to/from the ring
* enqueue/dequeue finish
Note that this API is available only for two sync modes:
* Single Producer/Single Consumer (SP/SC)
* Multi-producer/Multi-consumer with Head/Tail Sync (HTS)
It is a user responsibility to create/init ring with appropriate sync modes.
Following is an example of usage:
.. code-block:: c
/* Reserve space on the ring */
n = rte_ring_enqueue_zc_burst_start(r, 32, &zcd, NULL);
/* Pkt I/O core polls packets from the NIC */
if (n != 0) {
nb_rx = rte_eth_rx_burst(portid, queueid, zcd->ptr1, zcd->n1);
if (nb_rx == zcd->n1 && n != zcd->n1)
nb_rx += rte_eth_rx_burst(portid, queueid, zcd->ptr2,
n - zcd->n1);
/* Provide packets to the packet processing cores */
rte_ring_enqueue_zc_finish(r, nb_rx);
}
Note that between ``_start_`` and ``_finish_`` no other thread can proceed
with enqueue(/dequeue) operation till ``_finish_`` completes.
References
----------

9
doc/guides/rel_notes/release_20_11.rst
View File

@ -84,6 +84,15 @@ New Features
``rte_vect_set_max_simd_bitwidth`` function, or by the user with EAL flag
``--force-max-simd-bitwidth``.
* **Added zero copy APIs for rte_ring.**
For rings with producer/consumer in ``RTE_RING_SYNC_ST``, ``RTE_RING_SYNC_MT_HTS``
modes, these APIs split enqueue/dequeue operation into three phases
(enqueue/dequeue start, copy data to/from ring, enqueue/dequeue finish).
Along with the advantages of the peek APIs, these provide the ability to
copy the data to the ring memory directly without the need for temporary
storage.
* **Updated CRC modules of the net library.**
* Added runtime selection of the optimal architecture-specific CRC path.

1
lib/librte_ring/meson.build
View File

@ -11,5 +11,6 @@ headers = files('rte_ring.h',
'rte_ring_hts_c11_mem.h',
'rte_ring_peek.h',
'rte_ring_peek_c11_mem.h',
'rte_ring_peek_zc.h',
'rte_ring_rts.h',
'rte_ring_rts_c11_mem.h')

1
lib/librte_ring/rte_ring_elem.h
View File

@ -1079,6 +1079,7 @@ rte_ring_dequeue_burst_elem(struct rte_ring *r, void *obj_table,
#ifdef ALLOW_EXPERIMENTAL_API
#include <rte_ring_peek.h>
#include <rte_ring_peek_zc.h>
#endif
#include <rte_ring.h>

549
lib/librte_ring/rte_ring_peek_zc.h Normal file
View File

@ -0,0 +1,549 @@
/* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 2020 Arm Limited
* Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
* All rights reserved.
* Derived from FreeBSD's bufring.h
* Used as BSD-3 Licensed with permission from Kip Macy.
*/
#ifndef _RTE_RING_PEEK_ZC_H_
#define _RTE_RING_PEEK_ZC_H_
/**
* @file
* @b EXPERIMENTAL: this API may change without prior notice
* It is not recommended to include this file directly.
* Please include <rte_ring_elem.h> instead.
*
* Ring Peek Zero Copy APIs
* These APIs make it possible to split public enqueue/dequeue API
* into 3 parts:
* - enqueue/dequeue start
* - copy data to/from the ring
* - enqueue/dequeue finish
* Along with the advantages of the peek APIs, these APIs provide the ability
* to avoid copying of the data to temporary area (for ex: array of mbufs
* on the stack).
*
* Note that currently these APIs are available only for two sync modes:
* 1) Single Producer/Single Consumer (RTE_RING_SYNC_ST)
* 2) Serialized Producer/Serialized Consumer (RTE_RING_SYNC_MT_HTS).
* It is user's responsibility to create/init ring with appropriate sync
* modes selected.
*
* Following are some examples showing the API usage.
* 1)
* struct elem_obj {uint64_t a; uint32_t b, c;};
* struct elem_obj *obj;
*
* // Create ring with sync type RTE_RING_SYNC_ST or RTE_RING_SYNC_MT_HTS
* // Reserve space on the ring
* n = rte_ring_enqueue_zc_bulk_elem_start(r, sizeof(elem_obj), 1, &zcd, NULL);
*
* // Produce the data directly on the ring memory
* obj = (struct elem_obj *)zcd->ptr1;
* obj->a = rte_get_a();
* obj->b = rte_get_b();
* obj->c = rte_get_c();
* rte_ring_enqueue_zc_elem_finish(ring, n);
*
* 2)
* // Create ring with sync type RTE_RING_SYNC_ST or RTE_RING_SYNC_MT_HTS
* // Reserve space on the ring
* n = rte_ring_enqueue_zc_burst_start(r, 32, &zcd, NULL);
*
* // Pkt I/O core polls packets from the NIC
* if (n != 0) {
* nb_rx = rte_eth_rx_burst(portid, queueid, zcd->ptr1, zcd->n1);
* if (nb_rx == zcd->n1 && n != zcd->n1)
* nb_rx = rte_eth_rx_burst(portid, queueid,
* zcd->ptr2, n - zcd->n1);
*
* // Provide packets to the packet processing cores
* rte_ring_enqueue_zc_finish(r, nb_rx);
* }
*
* Note that between _start_ and _finish_ none other thread can proceed
* with enqueue/dequeue operation till _finish_ completes.
*/
#ifdef __cplusplus
extern "C" {
#endif
#include <rte_ring_peek_c11_mem.h>
/**
* Ring zero-copy information structure.
*
* This structure contains the pointers and length of the space
* reserved on the ring storage.
*/
struct rte_ring_zc_data {
/* Pointer to the first space in the ring */
void *ptr1;
/* Pointer to the second space in the ring if there is wrap-around.
* It contains valid value only if wrap-around happens.
*/
void *ptr2;
/* Number of elements in the first pointer. If this is equal to
* the number of elements requested, then ptr2 is NULL.
* Otherwise, subtracting n1 from number of elements requested
* will give the number of elements available at ptr2.
*/
unsigned int n1;
} __rte_cache_aligned;
static __rte_always_inline void
__rte_ring_get_elem_addr(struct rte_ring *r, uint32_t head,
uint32_t esize, uint32_t num, void **dst1, uint32_t *n1, void **dst2)
{
uint32_t idx, scale, nr_idx;
uint32_t *ring = (uint32_t *)&r[1];
/* Normalize to uint32_t */
scale = esize / sizeof(uint32_t);
idx = head & r->mask;
nr_idx = idx * scale;
*dst1 = ring + nr_idx;
*n1 = num;
if (idx + num > r->size) {
*n1 = r->size - idx;
*dst2 = ring;
} else {
*dst2 = NULL;
}
}
/**
* @internal This function moves prod head value.
*/
static __rte_always_inline unsigned int
__rte_ring_do_enqueue_zc_elem_start(struct rte_ring *r, unsigned int esize,
uint32_t n, enum rte_ring_queue_behavior behavior,
struct rte_ring_zc_data *zcd, unsigned int *free_space)
{
uint32_t free, head, next;
switch (r->prod.sync_type) {
case RTE_RING_SYNC_ST:
n = __rte_ring_move_prod_head(r, RTE_RING_SYNC_ST, n,
behavior, &head, &next, &free);
break;
case RTE_RING_SYNC_MT_HTS:
n = __rte_ring_hts_move_prod_head(r, n, behavior, &head, &free);
break;
case RTE_RING_SYNC_MT:
case RTE_RING_SYNC_MT_RTS:
default:
/* unsupported mode, shouldn't be here */
RTE_ASSERT(0);
n = 0;
free = 0;
return n;
}
__rte_ring_get_elem_addr(r, head, esize, n, &zcd->ptr1,
&zcd->n1, &zcd->ptr2);
if (free_space != NULL)
*free_space = free - n;
return n;
}
/**
* Start to enqueue several objects on the ring.
* Note that no actual objects are put in the queue by this function,
* it just reserves space for the user on the ring.
* User has to copy objects into the queue using the returned pointers.
* User should call rte_ring_enqueue_zc_elem_finish to complete the
* enqueue operation.
*
* @param r
* A pointer to the ring structure.
* @param esize
* The size of ring element, in bytes. It must be a multiple of 4.
* @param n
* The number of objects to add in the ring.
* @param zcd
* Structure containing the pointers and length of the space
* reserved on the ring storage.
* @param free_space
* If non-NULL, returns the amount of space in the ring after the
* reservation operation has finished.
* @return
* The number of objects that can be enqueued, either 0 or n
*/
__rte_experimental
static __rte_always_inline unsigned int
rte_ring_enqueue_zc_bulk_elem_start(struct rte_ring *r, unsigned int esize,
unsigned int n, struct rte_ring_zc_data *zcd, unsigned int *free_space)
{
return __rte_ring_do_enqueue_zc_elem_start(r, esize, n,
RTE_RING_QUEUE_FIXED, zcd, free_space);
}
/**
* Start to enqueue several pointers to objects on the ring.
* Note that no actual pointers are put in the queue by this function,
* it just reserves space for the user on the ring.
* User has to copy pointers to objects into the queue using the
* returned pointers.
* User should call rte_ring_enqueue_zc_finish to complete the
* enqueue operation.
*
* @param r
* A pointer to the ring structure.
* @param n
* The number of objects to add in the ring.
* @param zcd
* Structure containing the pointers and length of the space
* reserved on the ring storage.
* @param free_space
* If non-NULL, returns the amount of space in the ring after the
* reservation operation has finished.
* @return
* The number of objects that can be enqueued, either 0 or n
*/
__rte_experimental
static __rte_always_inline unsigned int
rte_ring_enqueue_zc_bulk_start(struct rte_ring *r, unsigned int n,
struct rte_ring_zc_data *zcd, unsigned int *free_space)
{
return rte_ring_enqueue_zc_bulk_elem_start(r, sizeof(uintptr_t), n,
zcd, free_space);
}
/**
* Start to enqueue several objects on the ring.
* Note that no actual objects are put in the queue by this function,
* it just reserves space for the user on the ring.
* User has to copy objects into the queue using the returned pointers.
* User should call rte_ring_enqueue_zc_elem_finish to complete the
* enqueue operation.
*
* @param r
* A pointer to the ring structure.
* @param esize
* The size of ring element, in bytes. It must be a multiple of 4.
* @param n
* The number of objects to add in the ring.
* @param zcd
* Structure containing the pointers and length of the space
* reserved on the ring storage.
* @param free_space
* If non-NULL, returns the amount of space in the ring after the
* reservation operation has finished.
* @return
* The number of objects that can be enqueued, either 0 or n
*/
__rte_experimental
static __rte_always_inline unsigned int
rte_ring_enqueue_zc_burst_elem_start(struct rte_ring *r, unsigned int esize,
unsigned int n, struct rte_ring_zc_data *zcd, unsigned int *free_space)
{
return __rte_ring_do_enqueue_zc_elem_start(r, esize, n,
RTE_RING_QUEUE_VARIABLE, zcd, free_space);
}
/**
* Start to enqueue several pointers to objects on the ring.
* Note that no actual pointers are put in the queue by this function,
* it just reserves space for the user on the ring.
* User has to copy pointers to objects into the queue using the
* returned pointers.
* User should call rte_ring_enqueue_zc_finish to complete the
* enqueue operation.
*
* @param r
* A pointer to the ring structure.
* @param n
* The number of objects to add in the ring.
* @param zcd
* Structure containing the pointers and length of the space
* reserved on the ring storage.
* @param free_space
* If non-NULL, returns the amount of space in the ring after the
* reservation operation has finished.
* @return
* The number of objects that can be enqueued, either 0 or n.
*/
__rte_experimental
static __rte_always_inline unsigned int
rte_ring_enqueue_zc_burst_start(struct rte_ring *r, unsigned int n,
struct rte_ring_zc_data *zcd, unsigned int *free_space)
{
return rte_ring_enqueue_zc_burst_elem_start(r, sizeof(uintptr_t), n,
zcd, free_space);
}
/**
* Complete enqueuing several objects on the ring.
* Note that number of objects to enqueue should not exceed previous
* enqueue_start return value.
*
* @param r
* A pointer to the ring structure.
* @param n
* The number of objects to add to the ring.
*/
__rte_experimental
static __rte_always_inline void
rte_ring_enqueue_zc_elem_finish(struct rte_ring *r, unsigned int n)
{
uint32_t tail;
switch (r->prod.sync_type) {
case RTE_RING_SYNC_ST:
n = __rte_ring_st_get_tail(&r->prod, &tail, n);
__rte_ring_st_set_head_tail(&r->prod, tail, n, 1);
break;
case RTE_RING_SYNC_MT_HTS:
n = __rte_ring_hts_get_tail(&r->hts_prod, &tail, n);
__rte_ring_hts_set_head_tail(&r->hts_prod, tail, n, 1);
break;
case RTE_RING_SYNC_MT:
case RTE_RING_SYNC_MT_RTS:
default:
/* unsupported mode, shouldn't be here */
RTE_ASSERT(0);
}
}
/**
* Complete enqueuing several pointers to objects on the ring.
* Note that number of objects to enqueue should not exceed previous
* enqueue_start return value.
*
* @param r
* A pointer to the ring structure.
* @param n
* The number of pointers to objects to add to the ring.
*/
__rte_experimental
static __rte_always_inline void
rte_ring_enqueue_zc_finish(struct rte_ring *r, unsigned int n)
{
rte_ring_enqueue_zc_elem_finish(r, n);
}
/**
* @internal This function moves cons head value and copies up to *n*
* objects from the ring to the user provided obj_table.
*/
static __rte_always_inline unsigned int
__rte_ring_do_dequeue_zc_elem_start(struct rte_ring *r,
uint32_t esize, uint32_t n, enum rte_ring_queue_behavior behavior,
struct rte_ring_zc_data *zcd, unsigned int *available)
{
uint32_t avail, head, next;
switch (r->cons.sync_type) {
case RTE_RING_SYNC_ST:
n = __rte_ring_move_cons_head(r, RTE_RING_SYNC_ST, n,
behavior, &head, &next, &avail);
break;
case RTE_RING_SYNC_MT_HTS:
n = __rte_ring_hts_move_cons_head(r, n, behavior,
&head, &avail);
break;
case RTE_RING_SYNC_MT:
case RTE_RING_SYNC_MT_RTS:
default:
/* unsupported mode, shouldn't be here */
RTE_ASSERT(0);
n = 0;
avail = 0;
return n;
}
__rte_ring_get_elem_addr(r, head, esize, n, &zcd->ptr1,
&zcd->n1, &zcd->ptr2);
if (available != NULL)
*available = avail - n;
return n;
}
/**
* Start to dequeue several objects from the ring.
* Note that no actual objects are copied from the queue by this function.
* User has to copy objects from the queue using the returned pointers.
* User should call rte_ring_dequeue_zc_elem_finish to complete the
* dequeue operation.
*
* @param r
* A pointer to the ring structure.
* @param esize
* The size of ring element, in bytes. It must be a multiple of 4.
* @param n
* The number of objects to remove from the ring.
* @param zcd
* Structure containing the pointers and length of the space
* reserved on the ring storage.
* @param available
* If non-NULL, returns the number of remaining ring entries after the
* dequeue has finished.
* @return
* The number of objects that can be dequeued, either 0 or n.
*/
__rte_experimental
static __rte_always_inline unsigned int
rte_ring_dequeue_zc_bulk_elem_start(struct rte_ring *r, unsigned int esize,
unsigned int n, struct rte_ring_zc_data *zcd, unsigned int *available)
{
return __rte_ring_do_dequeue_zc_elem_start(r, esize, n,
RTE_RING_QUEUE_FIXED, zcd, available);
}
/**
* Start to dequeue several pointers to objects from the ring.
* Note that no actual pointers are removed from the queue by this function.
* User has to copy pointers to objects from the queue using the
* returned pointers.
* User should call rte_ring_dequeue_zc_finish to complete the
* dequeue operation.
*
* @param r
* A pointer to the ring structure.
* @param n
* The number of objects to remove from the ring.
* @param zcd
* Structure containing the pointers and length of the space
* reserved on the ring storage.
* @param available
* If non-NULL, returns the number of remaining ring entries after the
* dequeue has finished.
* @return
* The number of objects that can be dequeued, either 0 or n.
*/
__rte_experimental
static __rte_always_inline unsigned int
rte_ring_dequeue_zc_bulk_start(struct rte_ring *r, unsigned int n,
struct rte_ring_zc_data *zcd, unsigned int *available)
{
return rte_ring_dequeue_zc_bulk_elem_start(r, sizeof(uintptr_t),
n, zcd, available);
}
/**
* Start to dequeue several objects from the ring.
* Note that no actual objects are copied from the queue by this function.
* User has to copy objects from the queue using the returned pointers.
* User should call rte_ring_dequeue_zc_elem_finish to complete the
* dequeue operation.
*
* @param r
* A pointer to the ring structure.
* @param esize
* The size of ring element, in bytes. It must be a multiple of 4.
* This must be the same value used while creating the ring. Otherwise
* the results are undefined.
* @param n
* The number of objects to dequeue from the ring.
* @param zcd
* Structure containing the pointers and length of the space
* reserved on the ring storage.
* @param available
* If non-NULL, returns the number of remaining ring entries after the
* dequeue has finished.
* @return
* The number of objects that can be dequeued, either 0 or n.
*/
__rte_experimental
static __rte_always_inline unsigned int
rte_ring_dequeue_zc_burst_elem_start(struct rte_ring *r, unsigned int esize,
unsigned int n, struct rte_ring_zc_data *zcd, unsigned int *available)
{
return __rte_ring_do_dequeue_zc_elem_start(r, esize, n,
RTE_RING_QUEUE_VARIABLE, zcd, available);
}
/**
* Start to dequeue several pointers to objects from the ring.
* Note that no actual pointers are removed from the queue by this function.
* User has to copy pointers to objects from the queue using the
* returned pointers.
* User should call rte_ring_dequeue_zc_finish to complete the
* dequeue operation.
*
* @param r
* A pointer to the ring structure.
* @param n
* The number of objects to remove from the ring.
* @param zcd
* Structure containing the pointers and length of the space
* reserved on the ring storage.
* @param available
* If non-NULL, returns the number of remaining ring entries after the
* dequeue has finished.
* @return
* The number of objects that can be dequeued, either 0 or n.
*/
__rte_experimental
static __rte_always_inline unsigned int
rte_ring_dequeue_zc_burst_start(struct rte_ring *r, unsigned int n,
struct rte_ring_zc_data *zcd, unsigned int *available)
{
return rte_ring_dequeue_zc_burst_elem_start(r, sizeof(uintptr_t), n,
zcd, available);
}
/**
* Complete dequeuing several objects from the ring.
* Note that number of objects to dequeued should not exceed previous
* dequeue_start return value.
*
* @param r
* A pointer to the ring structure.
* @param n
* The number of objects to remove from the ring.
*/
__rte_experimental
static __rte_always_inline void
rte_ring_dequeue_zc_elem_finish(struct rte_ring *r, unsigned int n)
{
uint32_t tail;
switch (r->cons.sync_type) {
case RTE_RING_SYNC_ST:
n = __rte_ring_st_get_tail(&r->cons, &tail, n);
__rte_ring_st_set_head_tail(&r->cons, tail, n, 0);
break;
case RTE_RING_SYNC_MT_HTS:
n = __rte_ring_hts_get_tail(&r->hts_cons, &tail, n);
__rte_ring_hts_set_head_tail(&r->hts_cons, tail, n, 0);
break;
case RTE_RING_SYNC_MT:
case RTE_RING_SYNC_MT_RTS:
default:
/* unsupported mode, shouldn't be here */
RTE_ASSERT(0);
}
}
/**
* Complete dequeuing several objects from the ring.
* Note that number of objects to dequeued should not exceed previous
* dequeue_start return value.
*
* @param r
* A pointer to the ring structure.
* @param n
* The number of objects to remove from the ring.
*/
__rte_experimental
static __rte_always_inline void
rte_ring_dequeue_zc_finish(struct rte_ring *r, unsigned int n)
{
rte_ring_dequeue_elem_finish(r, n);
}
#ifdef __cplusplus
}
#endif
#endif /* _RTE_RING_PEEK_ZC_H_ */