[dpdk-dev] [PATCH v3 0/2] add rte ring reset api and use it to flush a ring by hash

[dpdk-dev] [PATCH v3 0/2] add rte ring reset api and use it to flush a ring by hash

[Gavin Hu]

V3: Allow experimental API for meson build

V2: Fix the coding style issue(commit message line too long)

V1: To flush a ring not in use, dequeue one by one is wasting cpu cycles.
The patch is to just resetting the head and tail indices to save cpu
cycle.

Gavin Hu (2):
  ring: add reset api to flush the ring when not in use
  hash: flush the rings instead of dequeuing one by one

 lib/librte_hash/Makefile             |  2 +-
 lib/librte_hash/meson.build          |  3 +++
 lib/librte_hash/rte_cuckoo_hash.c    | 11 ++++-------
 lib/librte_ring/rte_ring.h           | 20 ++++++++++++++++++++
 lib/librte_ring/rte_ring_version.map |  7 +++++++
 5 files changed, 35 insertions(+), 8 deletions(-)

-- 
2.11.0

[dpdk-dev] [PATCH v3 1/2] ring: add reset api to flush the ring when not in use

[Gavin Hu]

Currently, the flush is done by dequeuing the ring in a while loop. It is
much simpler to flush the queue by resetting the head and tail indices.

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Ruifeng Wang <Ruifeng.Wang@arm.com>
Reviewed-by: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
---
 lib/librte_ring/rte_ring.h           | 20 ++++++++++++++++++++
 lib/librte_ring/rte_ring_version.map |  7 +++++++
 2 files changed, 27 insertions(+)

diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h
index af5444a9f..283030011 100644
--- a/lib/librte_ring/rte_ring.h
+++ b/lib/librte_ring/rte_ring.h
@@ -671,6 +671,26 @@ rte_ring_dequeue(struct rte_ring *r, void **obj_p)
 }
 
 /**
+ * Flush a ring.
+ *
+ * This function flush all the elements in a ring
+ *
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * @warning
+ * Make sure the ring is not in use while calling this function.
+ *
+ * @param r
+ *   A pointer to the ring structure.
+ */
+static inline void __rte_experimental
+rte_ring_reset(struct rte_ring *r)
+{
+	r->prod.head = r->cons.head = 0;
+	r->prod.tail = r->cons.tail = 0;
+}
+
+/**
  * Return the number of entries in a ring.
  *
  * @param r
diff --git a/lib/librte_ring/rte_ring_version.map b/lib/librte_ring/rte_ring_version.map
index d935efd0d..581d9cabe 100644
--- a/lib/librte_ring/rte_ring_version.map
+++ b/lib/librte_ring/rte_ring_version.map
@@ -17,3 +17,10 @@ DPDK_2.2 {
 	rte_ring_free;
 
 } DPDK_2.0;
+
+EXPERIMENTAL {
+    global:
+
+	rte_ring_reset;
+
+};
-- 
2.11.0

[dpdk-dev] [PATCH v3 2/2] hash: flush the rings instead of dequeuing one by one

[Gavin Hu]

Within rte_hash_reset, calling a while loop to dequeue one by
one from the ring, while not using them at all, is wasting cycles,
The patch just flush the ring by resetting the indices can save cpu
cycles.

Fixes: b26473ff8f4a ("hash: add reset function")
Fixes: 75706568a7eb ("hash: add extendable bucket feature")
Cc: stable@dpdk.org

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
---
 lib/librte_hash/Makefile          |  2 +-
 lib/librte_hash/meson.build       |  3 +++
 lib/librte_hash/rte_cuckoo_hash.c | 11 ++++-------
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/librte_hash/Makefile b/lib/librte_hash/Makefile
index c8c435dfd..5669d83f4 100644
--- a/lib/librte_hash/Makefile
+++ b/lib/librte_hash/Makefile
@@ -6,7 +6,7 @@ include $(RTE_SDK)/mk/rte.vars.mk
 # library name
 LIB = librte_hash.a
 
-CFLAGS += -O3
+CFLAGS += -O3 -DALLOW_EXPERIMENTAL_API
 CFLAGS += $(WERROR_FLAGS) -I$(SRCDIR)
 LDLIBS += -lrte_eal -lrte_ring
 
diff --git a/lib/librte_hash/meson.build b/lib/librte_hash/meson.build
index efc06ede5..ebf70de89 100644
--- a/lib/librte_hash/meson.build
+++ b/lib/librte_hash/meson.build
@@ -14,3 +14,6 @@ headers = files('rte_cmp_arm64.h',
 
 sources = files('rte_cuckoo_hash.c', 'rte_fbk_hash.c')
 deps += ['ring']
+
+# rte ring reset is not yet part of stable API
+allow_experimental_apis = true
diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index c55a4f263..2719af3ce 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -559,7 +559,6 @@ __hash_rw_reader_unlock(const struct rte_hash *h)
 void
 rte_hash_reset(struct rte_hash *h)
 {
-	void *ptr;
 	uint32_t tot_ring_cnt, i;
 
 	if (h == NULL)
@@ -570,16 +569,14 @@ rte_hash_reset(struct rte_hash *h)
 	memset(h->key_store, 0, h->key_entry_size * (h->entries + 1));
 	*h->tbl_chng_cnt = 0;
 
-	/* clear the free ring */
-	while (rte_ring_dequeue(h->free_slots, &ptr) == 0)
-		continue;
+	/* reset the free ring */
+	rte_ring_reset(h->free_slots);
 
-	/* clear free extendable bucket ring and memory */
+	/* flush free extendable bucket ring and memory */
 	if (h->ext_table_support) {
 		memset(h->buckets_ext, 0, h->num_buckets *
 						sizeof(struct rte_hash_bucket));
-		while (rte_ring_dequeue(h->free_ext_bkts, &ptr) == 0)
-			continue;
+		rte_ring_reset(h->free_ext_bkts);
 	}
 
 	/* Repopulate the free slots ring. Entry zero is reserved for key misses */
-- 
2.11.0

Re: [dpdk-dev] [PATCH v3 0/2] add rte ring reset api and use it to flush a ring by hash

[Thomas Monjalon]

+Cc Olivier, maintainer of the ring library.

12/12/2018 12:15, Gavin Hu:
> V3: Allow experimental API for meson build
> 
> V2: Fix the coding style issue(commit message line too long)
> 
> V1: To flush a ring not in use, dequeue one by one is wasting cpu cycles.
> The patch is to just resetting the head and tail indices to save cpu
> cycle.
> 
> Gavin Hu (2):
>   ring: add reset api to flush the ring when not in use
>   hash: flush the rings instead of dequeuing one by one
> 
>  lib/librte_hash/Makefile             |  2 +-
>  lib/librte_hash/meson.build          |  3 +++
>  lib/librte_hash/rte_cuckoo_hash.c    | 11 ++++-------
>  lib/librte_ring/rte_ring.h           | 20 ++++++++++++++++++++
>  lib/librte_ring/rte_ring_version.map |  7 +++++++
>  5 files changed, 35 insertions(+), 8 deletions(-)