[dpdk-dev] [PATCH] mempool/octeontx2: optimize for L1D cache architecture

[<pbhagavatula@marvell.com>]

From: Pavan Nikhilesh <pbhagavatula@marvell.com>

OCTEON TX2 has 8 sets, 41 ways L1D cache, VA<9:7> bits dictate
the set selection.
Add additional padding to ensure that the element size always
occupies odd number of cachelines to ensure even distribution
of elements among L1D cache sets.

Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
Signed-off-by: Nithin Dabilpuram <ndabilpuram@marvell.com>
Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
Signed-off-by: Jerin Jacob <jerinj@marvell.com>
---
 drivers/mempool/octeontx2/otx2_mempool_ops.c | 41 ++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/drivers/mempool/octeontx2/otx2_mempool_ops.c b/drivers/mempool/octeontx2/otx2_mempool_ops.c
index ea4b1c45d..bd71babdb 100644
--- a/drivers/mempool/octeontx2/otx2_mempool_ops.c
+++ b/drivers/mempool/octeontx2/otx2_mempool_ops.c
@@ -641,6 +641,7 @@ otx2_npa_alloc(struct rte_mempool *mp)
 	struct npa_aura_s aura;
 	struct npa_pool_s pool;
 	uint64_t aura_handle;
+	size_t padding;
 	int rc;
 
 	lf = otx2_npa_lf_obj_get();
@@ -650,6 +651,18 @@ otx2_npa_alloc(struct rte_mempool *mp)
 	}
 
 	block_size = mp->elt_size + mp->header_size + mp->trailer_size;
+	/*
+	 * OCTEON TX2 has 8 sets, 41 ways L1D cache, VA<9:7> bits dictate
+	 * the set selection.
+	 * Add additional padding to ensure that the element size always
+	 * occupies odd number of cachelines to ensure even distribution
+	 * of elements among L1D cache sets.
+	 */
+	padding = ((block_size / RTE_CACHE_LINE_SIZE) % 2) ? 0 :
+				RTE_CACHE_LINE_SIZE;
+	mp->trailer_size += padding;
+	block_size += padding;
+
 	block_count = mp->size;
 
 	if (block_size % OTX2_ALIGN != 0) {
@@ -724,12 +737,22 @@ otx2_npa_calc_mem_size(const struct rte_mempool *mp, uint32_t obj_num,
 						align);
 }
 
+static uint8_t
+otx2_npa_l1d_way_set_get(uint64_t iova)
+{
+	return (iova >> rte_log2_u32(RTE_CACHE_LINE_SIZE)) & 0x7;
+}
+
 static int
 otx2_npa_populate(struct rte_mempool *mp, unsigned int max_objs, void *vaddr,
 		  rte_iova_t iova, size_t len,
 		  rte_mempool_populate_obj_cb_t *obj_cb, void *obj_cb_arg)
 {
+#define OTX2_L1D_NB_SETS	8
+	uint64_t distribution[OTX2_L1D_NB_SETS];
+	rte_iova_t start_iova;
 	size_t total_elt_sz;
+	uint8_t set;
 	size_t off;
 
 	if (iova == RTE_BAD_IOVA)
@@ -743,10 +766,28 @@ otx2_npa_populate(struct rte_mempool *mp, unsigned int max_objs, void *vaddr,
 	if (len < off)
 		return -EINVAL;
 
+
 	vaddr = (char *)vaddr + off;
 	iova += off;
 	len -= off;
 
+	memset(distribution, 0, sizeof(uint64_t) * OTX2_L1D_NB_SETS);
+	start_iova = iova;
+	while (start_iova < iova + len) {
+		set = otx2_npa_l1d_way_set_get(start_iova + mp->header_size);
+		distribution[set]++;
+		start_iova += total_elt_sz;
+	}
+
+	otx2_npa_dbg("iova %lx, aligned iova %lx", iova - off, iova);
+	otx2_npa_dbg("length %ld, aligned length %ld", len + off, len);
+	otx2_npa_dbg("element size %ld", total_elt_sz);
+	otx2_npa_dbg("requested objects %d, possible objects %ld", max_objs,
+			len / total_elt_sz);
+	otx2_npa_dbg("L1D set distribution :");
+	for (int i = 0; i < OTX2_L1D_NB_SETS; i++)
+		otx2_npa_dbg("set[%d] : objects : %ld", i, distribution[i]);
+
 	npa_lf_aura_op_range_set(mp->pool_id, iova, iova + len);
 
 	if (npa_lf_aura_range_update_check(mp->pool_id) < 0)
-- 
2.17.1