> Subject: [PATCH v6 27/39] mempool: use C11 alignas
>
> The current location used for __rte_aligned(a) for alignment of types
> and variables is not compatible with MSVC. There is only a single
> location accepted by both toolchains.
>
> For variables standard C11 offers alignas(a) supported by conformant
> compilers i.e. both MSVC and GCC.
>
> For types the standard offers no alignment facility that compatibly
> interoperates with C and C++ but may be achieved by relocating the
> placement of __rte_aligned(a) to the aforementioned location accepted
> by all currently supported toolchains.
>
> To allow alignment for both compilers do the following:
>
> * Move __rte_aligned from the end of {struct,union} definitions to
> be between {struct,union} and tag.
>
> The placement between {struct,union} and the tag allows the desired
> alignment to be imparted on the type regardless of the toolchain being
> used for all of GCC, LLVM, MSVC compilers building both C and C++.
>
> * Replace use of __rte_aligned(a) on variables/fields with alignas(a).
>
> Signed-off-by: Tyler Retzlaff <roret...@linux.microsoft.com>
> Acked-by: Morten Brørup <m...@smartsharesystems.com>
> ---
> lib/mempool/rte_mempool.h | 27 ++++++++++++++-------------
> 1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/lib/mempool/rte_mempool.h b/lib/mempool/rte_mempool.h
> index 6fa4d48..23fd5c8 100644
> --- a/lib/mempool/rte_mempool.h
> +++ b/lib/mempool/rte_mempool.h
> @@ -34,6 +34,7 @@
> * user cache created with rte_mempool_cache_create().
> */
>
> +#include <stdalign.h>
> #include <stdio.h>
> #include <stdint.h>
> #include <inttypes.h>
> @@ -66,7 +67,7 @@
> * captured since they can be calculated from other stats.
> * For example: put_cache_objs = put_objs - put_common_pool_objs.
> */
> -struct rte_mempool_debug_stats {
> +struct __rte_cache_aligned rte_mempool_debug_stats {
> uint64_t put_bulk; /**< Number of puts. */
> uint64_t put_objs; /**< Number of objects successfully put.
> */
> uint64_t put_common_pool_bulk; /**< Number of bulks enqueued in common
> pool. */
> @@ -80,13 +81,13 @@ struct rte_mempool_debug_stats {
> uint64_t get_success_blks; /**< Successful allocation number of
> contiguous blocks. */
> uint64_t get_fail_blks; /**< Failed allocation number of
> contiguous blocks. */
> RTE_CACHE_GUARD;
> -} __rte_cache_aligned;
> +};
> #endif
>
> /**
> * A structure that stores a per-core object cache.
> */
> -struct rte_mempool_cache {
> +struct __rte_cache_aligned rte_mempool_cache {
> uint32_t size; /**< Size of the cache */
> uint32_t flushthresh; /**< Threshold before we flush excess elements */
> uint32_t len; /**< Current cache count */
> @@ -109,8 +110,8 @@ struct rte_mempool_cache {
> * Cache is allocated to this size to allow it to overflow in certain
> * cases to avoid needless emptying of cache.
> */
> - void *objs[RTE_MEMPOOL_CACHE_MAX_SIZE * 2] __rte_cache_aligned;
> -} __rte_cache_aligned;
> + alignas(RTE_CACHE_LINE_SIZE) void *objs[RTE_MEMPOOL_CACHE_MAX_SIZE * 2];
> +};
>
> /**
> * A structure that stores the size of mempool elements.
> @@ -218,15 +219,15 @@ struct rte_mempool_memhdr {
> * The structure is cache-line aligned to avoid ABI breakages in
> * a number of cases when something small is added.
> */
> -struct rte_mempool_info {
> +struct __rte_cache_aligned rte_mempool_info {
> /** Number of objects in the contiguous block */
> unsigned int contig_block_size;
> -} __rte_cache_aligned;
> +};
>
> /**
> * The RTE mempool structure.
> */
> -struct rte_mempool {
> +struct __rte_cache_aligned rte_mempool {
> char name[RTE_MEMPOOL_NAMESIZE]; /**< Name of mempool. */
> union {
> void *pool_data; /**< Ring or pool to store objects. */
> @@ -268,7 +269,7 @@ struct rte_mempool {
> */
> struct rte_mempool_debug_stats stats[RTE_MAX_LCORE + 1];
> #endif
> -} __rte_cache_aligned;
> +};
>
> /** Spreading among memory channels not required. */
> #define RTE_MEMPOOL_F_NO_SPREAD 0x0001
> @@ -688,7 +689,7 @@ typedef int (*rte_mempool_get_info_t)(const struct
> rte_mempool *mp,
>
>
> /** Structure defining mempool operations structure */
> -struct rte_mempool_ops {
> +struct __rte_cache_aligned rte_mempool_ops {
> char name[RTE_MEMPOOL_OPS_NAMESIZE]; /**< Name of mempool ops struct. */
> rte_mempool_alloc_t alloc; /**< Allocate private data. */
> rte_mempool_free_t free; /**< Free the external pool. */
> @@ -713,7 +714,7 @@ struct rte_mempool_ops {
> * Dequeue a number of contiguous object blocks.
> */
> rte_mempool_dequeue_contig_blocks_t dequeue_contig_blocks;
> -} __rte_cache_aligned;
> +};
>
> #define RTE_MEMPOOL_MAX_OPS_IDX 16 /**< Max registered ops structs */
>
> @@ -726,14 +727,14 @@ struct rte_mempool_ops {
> * any function pointers stored directly in the mempool struct would not be.
> * This results in us simply having "ops_index" in the mempool struct.
> */
> -struct rte_mempool_ops_table {
> +struct __rte_cache_aligned rte_mempool_ops_table {
> rte_spinlock_t sl; /**< Spinlock for add/delete. */
> uint32_t num_ops; /**< Number of used ops structs in the table. */
> /**
> * Storage for all possible ops structs.
> */
> struct rte_mempool_ops ops[RTE_MEMPOOL_MAX_OPS_IDX];
> -} __rte_cache_aligned;
> +};
>
> /** Array of registered ops structs. */
> extern struct rte_mempool_ops_table rte_mempool_ops_table;
> --
Acked-by: Konstantin Ananyev <konstantin.anan...@huawei.com>
> 1.8.3.1
