The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e5b2bc30c21139ae10f0e56989389d0bc7b7b1d6 Mon Sep 17 00:00:00 2001 From: Yevgeny Kliteynik kliteyn@nvidia.com Date: Fri, 24 Dec 2021 01:07:30 +0200 Subject: [PATCH] net/mlx5: DR, Cache STE shadow memory

During rule insertion on each ICM memory chunk we also allocate shadow memory used for management. This includes the hw_ste, dr_ste and miss list per entry. Since the scale of these allocations is large we noticed a performance hiccup that happens once malloc and free are stressed. In extreme usecases when ~1M chunks are freed at once, it might take up to 40 seconds to complete this, up to the point the kernel sees this as self-detected stall on CPU:

rcu: INFO: rcu_sched self-detected stall on CPU

To resolve this we will increase the reuse of shadow memory. Doing this we see that a time in the aforementioned usecase dropped from ~40 seconds to ~8-10 seconds.

Fixes: 29cf8febd185 ("net/mlx5: DR, ICM pool memory allocator") Signed-off-by: Alex Vesker valex@nvidia.com Signed-off-by: Yevgeny Kliteynik kliteyn@nvidia.com Signed-off-by: Saeed Mahameed saeedm@nvidia.com

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_icm_pool.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_icm_pool.c index 7f6fd9c5e371..f496b7e9401b 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_icm_pool.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_icm_pool.c @@ -136,37 +136,35 @@ static void dr_icm_pool_mr_destroy(struct mlx5dr_icm_mr *icm_mr) kvfree(icm_mr); }

-static int dr_icm_chunk_ste_init(struct mlx5dr_icm_chunk *chunk) +static int dr_icm_buddy_get_ste_size(struct mlx5dr_icm_buddy_mem *buddy) { - chunk->ste_arr = kvzalloc(chunk->num_of_entries * - sizeof(chunk->ste_arr[0]), GFP_KERNEL); - if (!chunk->ste_arr) - return -ENOMEM; - - chunk->hw_ste_arr = kvzalloc(chunk->num_of_entries * - DR_STE_SIZE_REDUCED, GFP_KERNEL); - if (!chunk->hw_ste_arr) - goto out_free_ste_arr; - - chunk->miss_list = kvmalloc(chunk->num_of_entries * - sizeof(chunk->miss_list[0]), GFP_KERNEL); - if (!chunk->miss_list) - goto out_free_hw_ste_arr; + /* We support only one type of STE size, both for ConnectX-5 and later + * devices. Once the support for match STE which has a larger tag is + * added (32B instead of 16B), the STE size for devices later than + * ConnectX-5 needs to account for that. + */ + return DR_STE_SIZE_REDUCED; +}

- return 0; +static void dr_icm_chunk_ste_init(struct mlx5dr_icm_chunk *chunk, int offset) +{ + struct mlx5dr_icm_buddy_mem *buddy = chunk->buddy_mem; + int index = offset / DR_STE_SIZE;

-out_free_hw_ste_arr: - kvfree(chunk->hw_ste_arr); -out_free_ste_arr: - kvfree(chunk->ste_arr); - return -ENOMEM; + chunk->ste_arr = &buddy->ste_arr[index]; + chunk->miss_list = &buddy->miss_list[index]; + chunk->hw_ste_arr = buddy->hw_ste_arr + + index * dr_icm_buddy_get_ste_size(buddy); }

static void dr_icm_chunk_ste_cleanup(struct mlx5dr_icm_chunk *chunk) { - kvfree(chunk->miss_list); - kvfree(chunk->hw_ste_arr); - kvfree(chunk->ste_arr); + struct mlx5dr_icm_buddy_mem *buddy = chunk->buddy_mem; + + memset(chunk->hw_ste_arr, 0, + chunk->num_of_entries * dr_icm_buddy_get_ste_size(buddy)); + memset(chunk->ste_arr, 0, + chunk->num_of_entries * sizeof(chunk->ste_arr[0])); }

static enum mlx5dr_icm_type @@ -189,6 +187,44 @@ static void dr_icm_chunk_destroy(struct mlx5dr_icm_chunk *chunk, kvfree(chunk); }

+static int dr_icm_buddy_init_ste_cache(struct mlx5dr_icm_buddy_mem *buddy) +{ + int num_of_entries = + mlx5dr_icm_pool_chunk_size_to_entries(buddy->pool->max_log_chunk_sz); + + buddy->ste_arr = kvcalloc(num_of_entries, + sizeof(struct mlx5dr_ste), GFP_KERNEL); + if (!buddy->ste_arr) + return -ENOMEM; + + /* Preallocate full STE size on non-ConnectX-5 devices since + * we need to support both full and reduced with the same cache. + */ + buddy->hw_ste_arr = kvcalloc(num_of_entries, + dr_icm_buddy_get_ste_size(buddy), GFP_KERNEL); + if (!buddy->hw_ste_arr) + goto free_ste_arr; + + buddy->miss_list = kvmalloc(num_of_entries * sizeof(struct list_head), GFP_KERNEL); + if (!buddy->miss_list) + goto free_hw_ste_arr; + + return 0; + +free_hw_ste_arr: + kvfree(buddy->hw_ste_arr); +free_ste_arr: + kvfree(buddy->ste_arr); + return -ENOMEM; +} + +static void dr_icm_buddy_cleanup_ste_cache(struct mlx5dr_icm_buddy_mem *buddy) +{ + kvfree(buddy->ste_arr); + kvfree(buddy->hw_ste_arr); + kvfree(buddy->miss_list); +} + static int dr_icm_buddy_create(struct mlx5dr_icm_pool *pool) { struct mlx5dr_icm_buddy_mem *buddy; @@ -208,11 +244,19 @@ static int dr_icm_buddy_create(struct mlx5dr_icm_pool *pool) buddy->icm_mr = icm_mr; buddy->pool = pool;

+ if (pool->icm_type == DR_ICM_TYPE_STE) { + /* Reduce allocations by preallocating and reusing the STE structures */ + if (dr_icm_buddy_init_ste_cache(buddy)) + goto err_cleanup_buddy; + } + /* add it to the -start- of the list in order to search in it first */ list_add(&buddy->list_node, &pool->buddy_mem_list);

return 0;

+err_cleanup_buddy: + mlx5dr_buddy_cleanup(buddy); err_free_buddy: kvfree(buddy); free_mr: @@ -234,6 +278,9 @@ static void dr_icm_buddy_destroy(struct mlx5dr_icm_buddy_mem *buddy)

mlx5dr_buddy_cleanup(buddy);

+ if (buddy->pool->icm_type == DR_ICM_TYPE_STE) + dr_icm_buddy_cleanup_ste_cache(buddy); + kvfree(buddy); }

@@ -261,26 +308,18 @@ dr_icm_chunk_create(struct mlx5dr_icm_pool *pool, chunk->byte_size = mlx5dr_icm_pool_chunk_size_to_byte(chunk_size, pool->icm_type); chunk->seg = seg; + chunk->buddy_mem = buddy_mem_pool;

- if (pool->icm_type == DR_ICM_TYPE_STE && dr_icm_chunk_ste_init(chunk)) { - mlx5dr_err(pool->dmn, - "Failed to init ste arrays (order: %d)\n", - chunk_size); - goto out_free_chunk; - } + if (pool->icm_type == DR_ICM_TYPE_STE) + dr_icm_chunk_ste_init(chunk, offset);

buddy_mem_pool->used_memory += chunk->byte_size; - chunk->buddy_mem = buddy_mem_pool; INIT_LIST_HEAD(&chunk->chunk_list);

/* chunk now is part of the used_list */ list_add_tail(&chunk->chunk_list, &buddy_mem_pool->used_list);

return chunk; - -out_free_chunk: - kvfree(chunk); - return NULL; }

static bool dr_icm_pool_is_sync_required(struct mlx5dr_icm_pool *pool) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/mlx5dr.h b/drivers/net/ethernet/mellanox/mlx5/core/steering/mlx5dr.h index c7c93131b762..dfa223415fe2 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/steering/mlx5dr.h +++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/mlx5dr.h @@ -160,6 +160,11 @@ struct mlx5dr_icm_buddy_mem { * sync_ste command sets them free. */ struct list_head hot_list; + + /* Memory optimisation */ + struct mlx5dr_ste *ste_arr; + struct list_head *miss_list; + u8 *hw_ste_arr; };

int mlx5dr_buddy_init(struct mlx5dr_icm_buddy_mem *buddy,