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author | Cong Wang | 2019-02-07 00:00:19 +0100 |
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committer | Saeed Mahameed | 2019-02-11 23:39:14 +0100 |
commit | 1fbf1252df0e4212e17f98130cb5372b3bc019b0 (patch) | |
tree | bfc11da988c68d2d5d18fbe09e738e3b8b3da7bf /drivers/net/ethernet/mellanox/mlx5/core/eq.c | |
parent | net/mlx5: Set ODP SRQ support in firmware (diff) | |
download | kernel-qcow2-linux-1fbf1252df0e4212e17f98130cb5372b3bc019b0.tar.gz kernel-qcow2-linux-1fbf1252df0e4212e17f98130cb5372b3bc019b0.tar.xz kernel-qcow2-linux-1fbf1252df0e4212e17f98130cb5372b3bc019b0.zip |
mlx5: use RCU lock in mlx5_eq_cq_get()
mlx5_eq_cq_get() is called in IRQ handler, the spinlock inside
gets a lot of contentions when we test some heavy workload
with 60 RX queues and 80 CPU's, and it is clearly shown in the
flame graph.
In fact, radix_tree_lookup() is perfectly fine with RCU read lock,
we don't have to take a spinlock on this hot path. This is pretty
much similar to commit 291c566a2891
("net/mlx4_core: Fix racy CQ (Completion Queue) free"). Slow paths
are still serialized with the spinlock, and with synchronize_irq()
it should be safe to just move the fast path to RCU read lock.
This patch itself reduces the latency by about 50% for our memcached
workload on a 4.14 kernel we test. In upstream, as pointed out by Saeed,
this spinlock gets some rework in commit 02d92f790364
("net/mlx5: CQ Database per EQ"), so the difference could be smaller.
Cc: Saeed Mahameed <saeedm@mellanox.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Diffstat (limited to 'drivers/net/ethernet/mellanox/mlx5/core/eq.c')
-rw-r--r-- | drivers/net/ethernet/mellanox/mlx5/core/eq.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eq.c b/drivers/net/ethernet/mellanox/mlx5/core/eq.c index ee04aab65a9f..7092457705a2 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/eq.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/eq.c @@ -114,11 +114,11 @@ static struct mlx5_core_cq *mlx5_eq_cq_get(struct mlx5_eq *eq, u32 cqn) struct mlx5_cq_table *table = &eq->cq_table; struct mlx5_core_cq *cq = NULL; - spin_lock(&table->lock); + rcu_read_lock(); cq = radix_tree_lookup(&table->tree, cqn); if (likely(cq)) mlx5_cq_hold(cq); - spin_unlock(&table->lock); + rcu_read_unlock(); return cq; } @@ -371,9 +371,9 @@ int mlx5_eq_add_cq(struct mlx5_eq *eq, struct mlx5_core_cq *cq) struct mlx5_cq_table *table = &eq->cq_table; int err; - spin_lock_irq(&table->lock); + spin_lock(&table->lock); err = radix_tree_insert(&table->tree, cq->cqn, cq); - spin_unlock_irq(&table->lock); + spin_unlock(&table->lock); return err; } @@ -383,9 +383,9 @@ int mlx5_eq_del_cq(struct mlx5_eq *eq, struct mlx5_core_cq *cq) struct mlx5_cq_table *table = &eq->cq_table; struct mlx5_core_cq *tmp; - spin_lock_irq(&table->lock); + spin_lock(&table->lock); tmp = radix_tree_delete(&table->tree, cq->cqn); - spin_unlock_irq(&table->lock); + spin_unlock(&table->lock); if (!tmp) { mlx5_core_warn(eq->dev, "cq 0x%x not found in eq 0x%x tree\n", eq->eqn, cq->cqn); |