[v4] mempool cache: add zero-copy get and put functions

Message ID 20221224115514.33476-1-mb@smartsharesystems.com (mailing list archive)
State Superseded, archived
Delegated to: Thomas Monjalon
Headers
Series [v4] mempool cache: add zero-copy get and put functions |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/iol-broadcom-Performance success Performance Testing PASS
ci/iol-intel-Functional success Functional Testing PASS
ci/iol-intel-Performance success Performance Testing PASS
ci/github-robot: build success github build: passed
ci/iol-aarch64-unit-testing success Testing PASS
ci/iol-x86_64-compile-testing success Testing PASS
ci/iol-abi-testing success Testing PASS
ci/iol-testing success Testing PASS
ci/iol-x86_64-unit-testing success Testing PASS
ci/iol-aarch64-compile-testing success Testing PASS
ci/Intel-compilation success Compilation OK
ci/intel-Testing success Testing PASS
ci/loongarch-compilation success Compilation OK
ci/loongarch-unit-testing success Unit Testing PASS

Commit Message

Morten Brørup Dec. 24, 2022, 11:55 a.m. UTC
  Zero-copy access to mempool caches is beneficial for PMD performance, and
must be provided by the mempool library to fix [Bug 1052] without a
performance regression.

[Bug 1052]: https://bugs.dpdk.org/show_bug.cgi?id=1052

v4:
* Fix checkpatch warnings.
v3:
* Bugfix: Respect the cache size; compare to the flush threshold instead
  of RTE_MEMPOOL_CACHE_MAX_SIZE.
* Added 'rewind' function for incomplete 'put' operations. (Konstantin)
* Replace RTE_ASSERTs with runtime checks of the request size.
  Instead of failing, return NULL if the request is too big. (Konstantin)
* Modified comparison to prevent overflow if n is really huge and len is
  non-zero.
* Updated the comments in the code.
v2:
* Fix checkpatch warnings.
* Fix missing registration of trace points.
* The functions are inline, so they don't go into the map file.
v1 changes from the RFC:
* Removed run-time parameter checks. (Honnappa)
  This is a hot fast path function; requiring correct application
  behaviour, i.e. function parameters must be valid.
* Added RTE_ASSERT for parameters instead.
  Code for this is only generated if built with RTE_ENABLE_ASSERT.
* Removed fallback when 'cache' parameter is not set. (Honnappa)
* Chose the simple get function; i.e. do not move the existing objects in
  the cache to the top of the new stack, just leave them at the bottom.
* Renamed the functions. Other suggestions are welcome, of course. ;-)
* Updated the function descriptions.
* Added the functions to trace_fp and version.map.

Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
---
 lib/mempool/mempool_trace_points.c |   9 ++
 lib/mempool/rte_mempool.h          | 165 +++++++++++++++++++++++++++++
 lib/mempool/rte_mempool_trace_fp.h |  23 ++++
 lib/mempool/version.map            |   5 +
 4 files changed, 202 insertions(+)
  

Comments

Andrew Rybchenko Dec. 27, 2022, 9:24 a.m. UTC | #1
On 12/24/22 14:55, Morten Brørup wrote:
> Zero-copy access to mempool caches is beneficial for PMD performance, and
> must be provided by the mempool library to fix [Bug 1052] without a
> performance regression.
> 
> [Bug 1052]: https://bugs.dpdk.org/show_bug.cgi?id=1052

Bugzilla ID: 1052

> 
> v4:
> * Fix checkpatch warnings.
> v3:
> * Bugfix: Respect the cache size; compare to the flush threshold instead
>    of RTE_MEMPOOL_CACHE_MAX_SIZE.
> * Added 'rewind' function for incomplete 'put' operations. (Konstantin)
> * Replace RTE_ASSERTs with runtime checks of the request size.
>    Instead of failing, return NULL if the request is too big. (Konstantin)
> * Modified comparison to prevent overflow if n is really huge and len is
>    non-zero.
> * Updated the comments in the code.
> v2:
> * Fix checkpatch warnings.
> * Fix missing registration of trace points.
> * The functions are inline, so they don't go into the map file.
> v1 changes from the RFC:
> * Removed run-time parameter checks. (Honnappa)
>    This is a hot fast path function; requiring correct application
>    behaviour, i.e. function parameters must be valid.
> * Added RTE_ASSERT for parameters instead.
>    Code for this is only generated if built with RTE_ENABLE_ASSERT.
> * Removed fallback when 'cache' parameter is not set. (Honnappa)
> * Chose the simple get function; i.e. do not move the existing objects in
>    the cache to the top of the new stack, just leave them at the bottom.
> * Renamed the functions. Other suggestions are welcome, of course. ;-)
> * Updated the function descriptions.
> * Added the functions to trace_fp and version.map.
> 
> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>

[snip]

> diff --git a/lib/mempool/rte_mempool.h b/lib/mempool/rte_mempool.h
> index 9f530db24b..00387e7543 100644
> --- a/lib/mempool/rte_mempool.h
> +++ b/lib/mempool/rte_mempool.h

[snip]

> @@ -1346,6 +1347,170 @@ rte_mempool_cache_flush(struct rte_mempool_cache *cache,
>   	cache->len = 0;
>   }
>   
> +/**
> + * @warning
> + * @b EXPERIMENTAL: This API may change, or be removed, without prior notice.
> + *
> + * Zero-copy put objects in a user-owned mempool cache backed by the specified mempool.
> + *
> + * @param cache
> + *   A pointer to the mempool cache.
> + * @param mp
> + *   A pointer to the mempool.
> + * @param n
> + *   The number of objects to be put in the mempool cache.
> + * @return
> + *   The pointer to where to put the objects in the mempool cache.
> + *   NULL if the request itself is too big for the cache, i.e.
> + *   exceeds the cache flush threshold.
> + */
> +__rte_experimental
> +static __rte_always_inline void *
> +rte_mempool_cache_zc_put_bulk(struct rte_mempool_cache *cache,
> +		struct rte_mempool *mp,
> +		unsigned int n)
> +{
> +	void **cache_objs;
> +
> +	RTE_ASSERT(cache != NULL);
> +	RTE_ASSERT(mp != NULL);
> +
> +	rte_mempool_trace_cache_zc_put_bulk(cache, mp, n);

Wouldn't it be better to do tracing nearby return value to
trace return value as well?

> +
> +	if (n <= cache->flushthresh - cache->len) {
> +		/*
> +		 * The objects can be added to the cache without crossing the
> +		 * flush threshold.
> +		 */
> +		cache_objs = &cache->objs[cache->len];
> +		cache->len += n;
> +	} else if (likely(n <= cache->flushthresh)) {
> +		/*
> +		 * The request itself fits into the cache.
> +		 * But first, the cache must be flushed to the backend, so
> +		 * adding the objects does not cross the flush threshold.
> +		 */
> +		cache_objs = &cache->objs[0];
> +		rte_mempool_ops_enqueue_bulk(mp, cache_objs, cache->len);
> +		cache->len = n;
> +	} else {
> +		/* The request itself is too big for the cache. */
> +		return NULL;
> +	}
> +
> +	RTE_MEMPOOL_CACHE_STAT_ADD(cache, put_bulk, 1);
> +	RTE_MEMPOOL_CACHE_STAT_ADD(cache, put_objs, n);

It duplicates put function code. Shouldn't put function use
this one to avoid duplication?

> +
> +	return cache_objs;
> +}
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: This API may change, or be removed, without prior notice.
> + *
> + * Zero-copy un-put objects in a user-owned mempool cache.
> + *
> + * @param cache
> + *   A pointer to the mempool cache.
> + * @param n
> + *   The number of objects not put in the mempool cache after calling
> + *   rte_mempool_cache_zc_put_bulk().
> + */
> +__rte_experimental
> +static __rte_always_inline void
> +rte_mempool_cache_zc_put_rewind(struct rte_mempool_cache *cache,
> +		unsigned int n)
> +{
> +	RTE_ASSERT(cache != NULL);
> +	RTE_ASSERT(n <= cache->len);
> +
> +	rte_mempool_trace_cache_zc_put_rewind(cache, n);
> +
> +	cache->len -= n;
> +
> +	RTE_MEMPOOL_CACHE_STAT_ADD(cache, put_objs, (int)-n);
> +}
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: This API may change, or be removed, without prior notice.
> + *
> + * Zero-copy get objects from a user-owned mempool cache backed by the specified mempool.
> + *
> + * @param cache
> + *   A pointer to the mempool cache.
> + * @param mp
> + *   A pointer to the mempool.
> + * @param n
> + *   The number of objects to prefetch into the mempool cache.
> + * @return
> + *   The pointer to the objects in the mempool cache.
> + *   NULL on error; i.e. the cache + the pool does not contain 'n' objects.
> + *   With rte_errno set to the error code of the mempool dequeue function,
> + *   or EINVAL if the request itself is too big for the cache, i.e.
> + *   exceeds the cache flush threshold.
> + */
> +__rte_experimental
> +static __rte_always_inline void *
> +rte_mempool_cache_zc_get_bulk(struct rte_mempool_cache *cache,
> +		struct rte_mempool *mp,
> +		unsigned int n)
> +{
> +	unsigned int len;
> +
> +	RTE_ASSERT(cache != NULL);
> +	RTE_ASSERT(mp != NULL);
> +
> +	rte_mempool_trace_cache_zc_get_bulk(cache, mp, n);
> +
> +	len = cache->len;
> +
> +	if (n <= len) {
> +		/* The request can be satisfied from the cache as is. */
> +		len -= n;
> +	} else if (likely(n <= cache->flushthresh)) {
> +		/*
> +		 * The request itself can be satisfied from the cache.
> +		 * But first, the cache must be filled from the backend;
> +		 * fetch size + requested - len objects.
> +		 */
> +		int ret;
> +		const unsigned int size = cache->size;
> +
> +		ret = rte_mempool_ops_dequeue_bulk(mp, &cache->objs[len], size + n - len);

If size is RTE_MEMPOOL_CACHE_MAX_SIZE and n is cache->flushthres (i.e. 
RTE_MEMPOOL_CACHE_MAX_SIZE * 1.5), we'll dequeue up to 
RTE_MEMPOOL_CACHE_MAX_SIZE * 2.5 objects
whereas cache objects size is just
RTE_MEMPOOL_CACHE_MAX_SIZE * 2. Am I missing something?


> +		if (unlikely(ret < 0)) {
> +			/*
> +			 * We are buffer constrained.
> +			 * Do not fill the cache, just satisfy the request.
> +			 */
> +			ret = rte_mempool_ops_dequeue_bulk(mp, &cache->objs[len], n - len);
> +			if (unlikely(ret < 0)) {
> +				/* Unable to satisfy the request. */
> +
> +				RTE_MEMPOOL_STAT_ADD(mp, get_fail_bulk, 1);
> +				RTE_MEMPOOL_STAT_ADD(mp, get_fail_objs, n);
> +
> +				rte_errno = -ret;
> +				return NULL;
> +			}
> +
> +			len = 0;
> +		} else
> +			len = size;

Curly brackets are required in else branch since if branch
above has curly brackets.

> +	} else {
> +		/* The request itself is too big for the cache. */
> +		rte_errno = EINVAL;
> +		return NULL;
> +	}
> +
> +	cache->len = len;
> +
> +	RTE_MEMPOOL_CACHE_STAT_ADD(cache, get_success_bulk, 1);
> +	RTE_MEMPOOL_CACHE_STAT_ADD(cache, get_success_objs, n);
> +
> +	return &cache->objs[len];
> +}
> +
>   /**
>    * @internal Put several objects back in the mempool; used internally.
>    * @param mp
  
Morten Brørup Dec. 27, 2022, 10:31 a.m. UTC | #2
> From: Andrew Rybchenko [mailto:andrew.rybchenko@oktetlabs.ru]
> Sent: Tuesday, 27 December 2022 10.24
> 
> On 12/24/22 14:55, Morten Brørup wrote:
> > Zero-copy access to mempool caches is beneficial for PMD performance,
> and
> > must be provided by the mempool library to fix [Bug 1052] without a
> > performance regression.
> >
> > [Bug 1052]: https://bugs.dpdk.org/show_bug.cgi?id=1052
> 
> Bugzilla ID: 1052
> 
> >
> > v4:
> > * Fix checkpatch warnings.
> > v3:
> > * Bugfix: Respect the cache size; compare to the flush threshold
> instead
> >    of RTE_MEMPOOL_CACHE_MAX_SIZE.
> > * Added 'rewind' function for incomplete 'put' operations.
> (Konstantin)
> > * Replace RTE_ASSERTs with runtime checks of the request size.
> >    Instead of failing, return NULL if the request is too big.
> (Konstantin)
> > * Modified comparison to prevent overflow if n is really huge and len
> is
> >    non-zero.
> > * Updated the comments in the code.
> > v2:
> > * Fix checkpatch warnings.
> > * Fix missing registration of trace points.
> > * The functions are inline, so they don't go into the map file.
> > v1 changes from the RFC:
> > * Removed run-time parameter checks. (Honnappa)
> >    This is a hot fast path function; requiring correct application
> >    behaviour, i.e. function parameters must be valid.
> > * Added RTE_ASSERT for parameters instead.
> >    Code for this is only generated if built with RTE_ENABLE_ASSERT.
> > * Removed fallback when 'cache' parameter is not set. (Honnappa)
> > * Chose the simple get function; i.e. do not move the existing
> objects in
> >    the cache to the top of the new stack, just leave them at the
> bottom.
> > * Renamed the functions. Other suggestions are welcome, of course. ;-
> )
> > * Updated the function descriptions.
> > * Added the functions to trace_fp and version.map.
> >
> > Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> 
> [snip]
> 
> > diff --git a/lib/mempool/rte_mempool.h b/lib/mempool/rte_mempool.h
> > index 9f530db24b..00387e7543 100644
> > --- a/lib/mempool/rte_mempool.h
> > +++ b/lib/mempool/rte_mempool.h
> 
> [snip]
> 
> > @@ -1346,6 +1347,170 @@ rte_mempool_cache_flush(struct
> rte_mempool_cache *cache,
> >   	cache->len = 0;
> >   }
> >
> > +/**
> > + * @warning
> > + * @b EXPERIMENTAL: This API may change, or be removed, without
> prior notice.
> > + *
> > + * Zero-copy put objects in a user-owned mempool cache backed by the
> specified mempool.
> > + *
> > + * @param cache
> > + *   A pointer to the mempool cache.
> > + * @param mp
> > + *   A pointer to the mempool.
> > + * @param n
> > + *   The number of objects to be put in the mempool cache.
> > + * @return
> > + *   The pointer to where to put the objects in the mempool cache.
> > + *   NULL if the request itself is too big for the cache, i.e.
> > + *   exceeds the cache flush threshold.
> > + */
> > +__rte_experimental
> > +static __rte_always_inline void *
> > +rte_mempool_cache_zc_put_bulk(struct rte_mempool_cache *cache,
> > +		struct rte_mempool *mp,
> > +		unsigned int n)
> > +{
> > +	void **cache_objs;
> > +
> > +	RTE_ASSERT(cache != NULL);
> > +	RTE_ASSERT(mp != NULL);
> > +
> > +	rte_mempool_trace_cache_zc_put_bulk(cache, mp, n);
> 
> Wouldn't it be better to do tracing nearby return value to
> trace return value as well?

The existing mempool put operations have trace at the beginning, so I followed that convention. Considering that rte_mempool_do_generic_put() may call rte_mempool_ops_enqueue_bulk(), this convention ensures that trace output is emitted in the same order as the functions are called. I think this is the correct way of tracing.

> 
> > +
> > +	if (n <= cache->flushthresh - cache->len) {
> > +		/*
> > +		 * The objects can be added to the cache without crossing
> the
> > +		 * flush threshold.
> > +		 */
> > +		cache_objs = &cache->objs[cache->len];
> > +		cache->len += n;
> > +	} else if (likely(n <= cache->flushthresh)) {
> > +		/*
> > +		 * The request itself fits into the cache.
> > +		 * But first, the cache must be flushed to the backend, so
> > +		 * adding the objects does not cross the flush threshold.
> > +		 */
> > +		cache_objs = &cache->objs[0];
> > +		rte_mempool_ops_enqueue_bulk(mp, cache_objs, cache->len);
> > +		cache->len = n;
> > +	} else {
> > +		/* The request itself is too big for the cache. */
> > +		return NULL;
> > +	}
> > +
> > +	RTE_MEMPOOL_CACHE_STAT_ADD(cache, put_bulk, 1);
> > +	RTE_MEMPOOL_CACHE_STAT_ADD(cache, put_objs, n);
> 
> It duplicates put function code. Shouldn't put function use
> this one to avoid duplication?

Calling it from the put function would emit confusing trace output, indicating that the zero-copy put function was called - which it was, but not from the application.

I get your point about code duplication, so I will move its innards to an internal function (without trace), and call that function from both the existing put function and the new zero-copy put function (which will become a thin wrapper function, to also call the trace).

> 
> > +
> > +	return cache_objs;
> > +}
> > +
> > +/**
> > + * @warning
> > + * @b EXPERIMENTAL: This API may change, or be removed, without
> prior notice.
> > + *
> > + * Zero-copy un-put objects in a user-owned mempool cache.
> > + *
> > + * @param cache
> > + *   A pointer to the mempool cache.
> > + * @param n
> > + *   The number of objects not put in the mempool cache after
> calling
> > + *   rte_mempool_cache_zc_put_bulk().
> > + */
> > +__rte_experimental
> > +static __rte_always_inline void
> > +rte_mempool_cache_zc_put_rewind(struct rte_mempool_cache *cache,
> > +		unsigned int n)
> > +{
> > +	RTE_ASSERT(cache != NULL);
> > +	RTE_ASSERT(n <= cache->len);
> > +
> > +	rte_mempool_trace_cache_zc_put_rewind(cache, n);
> > +
> > +	cache->len -= n;
> > +
> > +	RTE_MEMPOOL_CACHE_STAT_ADD(cache, put_objs, (int)-n);
> > +}
> > +
> > +/**
> > + * @warning
> > + * @b EXPERIMENTAL: This API may change, or be removed, without
> prior notice.
> > + *
> > + * Zero-copy get objects from a user-owned mempool cache backed by
> the specified mempool.
> > + *
> > + * @param cache
> > + *   A pointer to the mempool cache.
> > + * @param mp
> > + *   A pointer to the mempool.
> > + * @param n
> > + *   The number of objects to prefetch into the mempool cache.
> > + * @return
> > + *   The pointer to the objects in the mempool cache.
> > + *   NULL on error; i.e. the cache + the pool does not contain 'n'
> objects.
> > + *   With rte_errno set to the error code of the mempool dequeue
> function,
> > + *   or EINVAL if the request itself is too big for the cache, i.e.
> > + *   exceeds the cache flush threshold.
> > + */
> > +__rte_experimental
> > +static __rte_always_inline void *
> > +rte_mempool_cache_zc_get_bulk(struct rte_mempool_cache *cache,
> > +		struct rte_mempool *mp,
> > +		unsigned int n)
> > +{
> > +	unsigned int len;
> > +
> > +	RTE_ASSERT(cache != NULL);
> > +	RTE_ASSERT(mp != NULL);
> > +
> > +	rte_mempool_trace_cache_zc_get_bulk(cache, mp, n);
> > +
> > +	len = cache->len;
> > +
> > +	if (n <= len) {
> > +		/* The request can be satisfied from the cache as is. */
> > +		len -= n;
> > +	} else if (likely(n <= cache->flushthresh)) {
> > +		/*
> > +		 * The request itself can be satisfied from the cache.
> > +		 * But first, the cache must be filled from the backend;
> > +		 * fetch size + requested - len objects.
> > +		 */
> > +		int ret;
> > +		const unsigned int size = cache->size;
> > +
> > +		ret = rte_mempool_ops_dequeue_bulk(mp, &cache->objs[len],
> size + n - len);
> 
> If size is RTE_MEMPOOL_CACHE_MAX_SIZE and n is cache->flushthres (i.e.
> RTE_MEMPOOL_CACHE_MAX_SIZE * 1.5), we'll dequeue up to
> RTE_MEMPOOL_CACHE_MAX_SIZE * 2.5 objects
> whereas cache objects size is just
> RTE_MEMPOOL_CACHE_MAX_SIZE * 2. Am I missing something?

Good catch! I must compare n to cache->size to avoid this.

> 
> 
> > +		if (unlikely(ret < 0)) {
> > +			/*
> > +			 * We are buffer constrained.
> > +			 * Do not fill the cache, just satisfy the request.
> > +			 */
> > +			ret = rte_mempool_ops_dequeue_bulk(mp, &cache-
> >objs[len], n - len);
> > +			if (unlikely(ret < 0)) {
> > +				/* Unable to satisfy the request. */
> > +
> > +				RTE_MEMPOOL_STAT_ADD(mp, get_fail_bulk, 1);
> > +				RTE_MEMPOOL_STAT_ADD(mp, get_fail_objs, n);
> > +
> > +				rte_errno = -ret;
> > +				return NULL;
> > +			}
> > +
> > +			len = 0;
> > +		} else
> > +			len = size;
> 
> Curly brackets are required in else branch since if branch
> above has curly brackets.

Thanks. I also thought this looked silly. It would be nice if checkpatch emitted a warning here.

> 
> > +	} else {
> > +		/* The request itself is too big for the cache. */
> > +		rte_errno = EINVAL;
> > +		return NULL;
> > +	}
> > +
> > +	cache->len = len;
> > +
> > +	RTE_MEMPOOL_CACHE_STAT_ADD(cache, get_success_bulk, 1);
> > +	RTE_MEMPOOL_CACHE_STAT_ADD(cache, get_success_objs, n);
> > +
> > +	return &cache->objs[len];
> > +}
> > +
> >   /**
> >    * @internal Put several objects back in the mempool; used
> internally.
> >    * @param mp
>
  

Patch

diff --git a/lib/mempool/mempool_trace_points.c b/lib/mempool/mempool_trace_points.c
index 4ad76deb34..83d353a764 100644
--- a/lib/mempool/mempool_trace_points.c
+++ b/lib/mempool/mempool_trace_points.c
@@ -77,3 +77,12 @@  RTE_TRACE_POINT_REGISTER(rte_mempool_trace_ops_free,
 
 RTE_TRACE_POINT_REGISTER(rte_mempool_trace_set_ops_byname,
 	lib.mempool.set.ops.byname)
+
+RTE_TRACE_POINT_REGISTER(rte_mempool_trace_cache_zc_put_bulk,
+	lib.mempool.cache.zc.put.bulk)
+
+RTE_TRACE_POINT_REGISTER(rte_mempool_trace_cache_zc_put_rewind,
+	lib.mempool.cache.zc.put.rewind)
+
+RTE_TRACE_POINT_REGISTER(rte_mempool_trace_cache_zc_get_bulk,
+	lib.mempool.cache.zc.get.bulk)
diff --git a/lib/mempool/rte_mempool.h b/lib/mempool/rte_mempool.h
index 9f530db24b..00387e7543 100644
--- a/lib/mempool/rte_mempool.h
+++ b/lib/mempool/rte_mempool.h
@@ -47,6 +47,7 @@ 
 #include <rte_ring.h>
 #include <rte_memcpy.h>
 #include <rte_common.h>
+#include <rte_errno.h>
 
 #include "rte_mempool_trace_fp.h"
 
@@ -1346,6 +1347,170 @@  rte_mempool_cache_flush(struct rte_mempool_cache *cache,
 	cache->len = 0;
 }
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: This API may change, or be removed, without prior notice.
+ *
+ * Zero-copy put objects in a user-owned mempool cache backed by the specified mempool.
+ *
+ * @param cache
+ *   A pointer to the mempool cache.
+ * @param mp
+ *   A pointer to the mempool.
+ * @param n
+ *   The number of objects to be put in the mempool cache.
+ * @return
+ *   The pointer to where to put the objects in the mempool cache.
+ *   NULL if the request itself is too big for the cache, i.e.
+ *   exceeds the cache flush threshold.
+ */
+__rte_experimental
+static __rte_always_inline void *
+rte_mempool_cache_zc_put_bulk(struct rte_mempool_cache *cache,
+		struct rte_mempool *mp,
+		unsigned int n)
+{
+	void **cache_objs;
+
+	RTE_ASSERT(cache != NULL);
+	RTE_ASSERT(mp != NULL);
+
+	rte_mempool_trace_cache_zc_put_bulk(cache, mp, n);
+
+	if (n <= cache->flushthresh - cache->len) {
+		/*
+		 * The objects can be added to the cache without crossing the
+		 * flush threshold.
+		 */
+		cache_objs = &cache->objs[cache->len];
+		cache->len += n;
+	} else if (likely(n <= cache->flushthresh)) {
+		/*
+		 * The request itself fits into the cache.
+		 * But first, the cache must be flushed to the backend, so
+		 * adding the objects does not cross the flush threshold.
+		 */
+		cache_objs = &cache->objs[0];
+		rte_mempool_ops_enqueue_bulk(mp, cache_objs, cache->len);
+		cache->len = n;
+	} else {
+		/* The request itself is too big for the cache. */
+		return NULL;
+	}
+
+	RTE_MEMPOOL_CACHE_STAT_ADD(cache, put_bulk, 1);
+	RTE_MEMPOOL_CACHE_STAT_ADD(cache, put_objs, n);
+
+	return cache_objs;
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: This API may change, or be removed, without prior notice.
+ *
+ * Zero-copy un-put objects in a user-owned mempool cache.
+ *
+ * @param cache
+ *   A pointer to the mempool cache.
+ * @param n
+ *   The number of objects not put in the mempool cache after calling
+ *   rte_mempool_cache_zc_put_bulk().
+ */
+__rte_experimental
+static __rte_always_inline void
+rte_mempool_cache_zc_put_rewind(struct rte_mempool_cache *cache,
+		unsigned int n)
+{
+	RTE_ASSERT(cache != NULL);
+	RTE_ASSERT(n <= cache->len);
+
+	rte_mempool_trace_cache_zc_put_rewind(cache, n);
+
+	cache->len -= n;
+
+	RTE_MEMPOOL_CACHE_STAT_ADD(cache, put_objs, (int)-n);
+}
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: This API may change, or be removed, without prior notice.
+ *
+ * Zero-copy get objects from a user-owned mempool cache backed by the specified mempool.
+ *
+ * @param cache
+ *   A pointer to the mempool cache.
+ * @param mp
+ *   A pointer to the mempool.
+ * @param n
+ *   The number of objects to prefetch into the mempool cache.
+ * @return
+ *   The pointer to the objects in the mempool cache.
+ *   NULL on error; i.e. the cache + the pool does not contain 'n' objects.
+ *   With rte_errno set to the error code of the mempool dequeue function,
+ *   or EINVAL if the request itself is too big for the cache, i.e.
+ *   exceeds the cache flush threshold.
+ */
+__rte_experimental
+static __rte_always_inline void *
+rte_mempool_cache_zc_get_bulk(struct rte_mempool_cache *cache,
+		struct rte_mempool *mp,
+		unsigned int n)
+{
+	unsigned int len;
+
+	RTE_ASSERT(cache != NULL);
+	RTE_ASSERT(mp != NULL);
+
+	rte_mempool_trace_cache_zc_get_bulk(cache, mp, n);
+
+	len = cache->len;
+
+	if (n <= len) {
+		/* The request can be satisfied from the cache as is. */
+		len -= n;
+	} else if (likely(n <= cache->flushthresh)) {
+		/*
+		 * The request itself can be satisfied from the cache.
+		 * But first, the cache must be filled from the backend;
+		 * fetch size + requested - len objects.
+		 */
+		int ret;
+		const unsigned int size = cache->size;
+
+		ret = rte_mempool_ops_dequeue_bulk(mp, &cache->objs[len], size + n - len);
+		if (unlikely(ret < 0)) {
+			/*
+			 * We are buffer constrained.
+			 * Do not fill the cache, just satisfy the request.
+			 */
+			ret = rte_mempool_ops_dequeue_bulk(mp, &cache->objs[len], n - len);
+			if (unlikely(ret < 0)) {
+				/* Unable to satisfy the request. */
+
+				RTE_MEMPOOL_STAT_ADD(mp, get_fail_bulk, 1);
+				RTE_MEMPOOL_STAT_ADD(mp, get_fail_objs, n);
+
+				rte_errno = -ret;
+				return NULL;
+			}
+
+			len = 0;
+		} else
+			len = size;
+	} else {
+		/* The request itself is too big for the cache. */
+		rte_errno = EINVAL;
+		return NULL;
+	}
+
+	cache->len = len;
+
+	RTE_MEMPOOL_CACHE_STAT_ADD(cache, get_success_bulk, 1);
+	RTE_MEMPOOL_CACHE_STAT_ADD(cache, get_success_objs, n);
+
+	return &cache->objs[len];
+}
+
 /**
  * @internal Put several objects back in the mempool; used internally.
  * @param mp
diff --git a/lib/mempool/rte_mempool_trace_fp.h b/lib/mempool/rte_mempool_trace_fp.h
index ed060e887c..14666457f7 100644
--- a/lib/mempool/rte_mempool_trace_fp.h
+++ b/lib/mempool/rte_mempool_trace_fp.h
@@ -109,6 +109,29 @@  RTE_TRACE_POINT_FP(
 	rte_trace_point_emit_ptr(mempool);
 )
 
+RTE_TRACE_POINT_FP(
+	rte_mempool_trace_cache_zc_put_bulk,
+	RTE_TRACE_POINT_ARGS(void *cache, void *mempool, uint32_t nb_objs),
+	rte_trace_point_emit_ptr(cache);
+	rte_trace_point_emit_ptr(mempool);
+	rte_trace_point_emit_u32(nb_objs);
+)
+
+RTE_TRACE_POINT_FP(
+	rte_mempool_trace_cache_zc_put_rewind,
+	RTE_TRACE_POINT_ARGS(void *cache, uint32_t nb_objs),
+	rte_trace_point_emit_ptr(cache);
+	rte_trace_point_emit_u32(nb_objs);
+)
+
+RTE_TRACE_POINT_FP(
+	rte_mempool_trace_cache_zc_get_bulk,
+	RTE_TRACE_POINT_ARGS(void *cache, void *mempool, uint32_t nb_objs),
+	rte_trace_point_emit_ptr(cache);
+	rte_trace_point_emit_ptr(mempool);
+	rte_trace_point_emit_u32(nb_objs);
+)
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/mempool/version.map b/lib/mempool/version.map
index b67d7aace7..1383ae6db2 100644
--- a/lib/mempool/version.map
+++ b/lib/mempool/version.map
@@ -63,6 +63,11 @@  EXPERIMENTAL {
 	__rte_mempool_trace_ops_alloc;
 	__rte_mempool_trace_ops_free;
 	__rte_mempool_trace_set_ops_byname;
+
+	# added in 23.03
+	__rte_mempool_trace_cache_zc_put_bulk;
+	__rte_mempool_trace_cache_zc_put_rewind;
+	__rte_mempool_trace_cache_zc_get_bulk;
 };
 
 INTERNAL {