path: root/drivers/net/mlx5/mlx5_rxtx_vec.h
diff options
authorYongseok Koh <>2018-05-09 04:09:04 -0700
committerFerruh Yigit <>2018-05-14 22:31:51 +0100
commit974f1e7ef146ffa112ab1a2afaf5db0360bc159f (patch)
treee1f9d27ede46a3fdc973eaa4f2890437d5bf9e14 /drivers/net/mlx5/mlx5_rxtx_vec.h
parentd561b5dc133fd98ddfa2dde237b1aa1d73e4df76 (diff)
net/mlx5: add new memory region support
This is the new design of Memory Region (MR) for mlx PMD, in order to: - Accommodate the new memory hotplug model. - Support non-contiguous Mempool. There are multiple layers for MR search. L0 is to look up the last-hit entry which is pointed by mr_ctrl->mru (Most Recently Used). If L0 misses, L1 is to look up the address in a fixed-sized array by linear search. L0/L1 is in an inline function - mlx5_mr_lookup_cache(). If L1 misses, the bottom-half function is called to look up the address from the bigger local cache of the queue. This is L2 - mlx5_mr_addr2mr_bh() and it is not an inline function. Data structure for L2 is the Binary Tree. If L2 misses, the search falls into the slowest path which takes locks in order to access global device cache (priv->mr.cache) which is also a B-tree and caches the original MR list (priv->mr.mr_list) of the device. Unless the global cache is overflowed, it is all-inclusive of the MR list. This is L3 - mlx5_mr_lookup_dev(). The size of the L3 cache table is limited and can't be expanded on the fly due to deadlock. Refer to the comments in the code for the details - mr_lookup_dev(). If L3 is overflowed, the list will have to be searched directly bypassing the cache although it is slower. If L3 misses, a new MR for the address should be created - mlx5_mr_create(). When it creates a new MR, it tries to register adjacent memsegs as much as possible which are virtually contiguous around the address. This must take two locks - memory_hotplug_lock and priv->mr.rwlock. Due to memory_hotplug_lock, there can't be any allocation/free of memory inside. In the free callback of the memory hotplug event, freed space is searched from the MR list and corresponding bits are cleared from the bitmap of MRs. This can fragment a MR and the MR will have multiple search entries in the caches. Once there's a change by the event, the global cache must be rebuilt and all the per-queue caches will be flushed as well. If memory is frequently freed in run-time, that may cause jitter on dataplane processing in the worst case by incurring MR cache flush and rebuild. But, it would be the least probable scenario. To guarantee the most optimal performance, it is highly recommended to use an EAL option - '--socket-mem'. Then, the reserved memory will be pinned and won't be freed dynamically. And it is also recommended to configure per-lcore cache of Mempool. Even though there're many MRs for a device or MRs are highly fragmented, the cache of Mempool will be much helpful to reduce misses on per-queue caches anyway. '--legacy-mem' is also supported. Signed-off-by: Yongseok Koh <>
Diffstat (limited to 'drivers/net/mlx5/mlx5_rxtx_vec.h')
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/net/mlx5/mlx5_rxtx_vec.h b/drivers/net/mlx5/mlx5_rxtx_vec.h
index 56c5a1b..6444283 100644
--- a/drivers/net/mlx5/mlx5_rxtx_vec.h
+++ b/drivers/net/mlx5/mlx5_rxtx_vec.h
@@ -99,9 +99,13 @@ mlx5_rx_replenish_bulk_mbuf(struct mlx5_rxq_data *rxq, uint16_t n)
rxq->stats.rx_nombuf += n;
- for (i = 0; i < n; ++i)
+ for (i = 0; i < n; ++i) {
wq[i].addr = rte_cpu_to_be_64((uintptr_t)elts[i]->buf_addr +
+ /* If there's only one MR, no need to replace LKey in WQE. */
+ if (unlikely(mlx5_mr_btree_len(&rxq->mr_ctrl.cache_bh) > 1))
+ wq[i].lkey = mlx5_rx_mb2mr(rxq, elts[i]);
+ }
rxq->rq_ci += n;
/* Prevent overflowing into consumed mbufs. */
elts_idx = rxq->rq_ci & q_mask;