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 <m...@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(+) 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 { -- 2.17.1
