Re: [dpdk-dev] [PATCH v1] common/mlx5: fix mlx5 aligned malloc

[Raslan Darawsheh]

Hi,

> -----Original Message-----
> From: Ophir Munk <ophi...@nvidia.com>
> Sent: Wednesday, September 9, 2020 11:43 AM
> To: dev@dpdk.org
> Cc: Raslan Darawsheh <rasl...@nvidia.com>; Ophir Munk
> <ophi...@nvidia.com>; Matan Azrad <ma...@nvidia.com>;
> sta...@dpdk.org
> Subject: [PATCH v1] common/mlx5: fix mlx5 aligned malloc
> 
> Before this commit system call memalign was used for aligned
> allocations, however memalign is deprecated.
> 
> Based on (1) - POSIX requires that memory aligned allocations can be
> freed using free. Some systems provide no way to reclaim memory
> allocated with memalign (because one can only pass to free a pointer
> gotten from malloc, while, memalign would call malloc and then align the
> obtained value).
> Another issue is that 64/32 bits architectures use a minimal alignment
> size. So any requested alignment below the minimal system size can be
> simplified by calling malloc.
> 
> The glibc implementation allows memory obtained from posix_memalign to
> be reclaimed with free.  This commit replaces system call memalign with
> system call posix_memalign. It also calls malloc in case the requested
> alignment is below the minimal system size.
> 
> (1)
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flinux
> .die.net%2Fman%2F3%2Fmemalign&amp;data=02%7C01%7Crasland%40nvid
> ia.com%7C28fa36f0f5544ee01f4a08d8549c7c57%7C43083d15727340c1b7db39
> efd9ccc17a%7C0%7C0%7C637352378361232944&amp;sdata=T73x%2FmnZHK
> 3Yl9fI17Orar%2FpCoXtHpQzZvdy47OckxA%3D&amp;reserved=0
> 
> Fixes: d38e3d526657 ("common/mlx5: add memory management functions")
> Cc: sta...@dpdk.org
> 
> Signed-off-by: Ophir Munk <ophi...@nvidia.com>
> Acked-by: Matan Azrad <ma...@mellanox.com>
> ---
>  drivers/common/mlx5/mlx5_malloc.c | 13 +++++++++----
>  drivers/common/mlx5/mlx5_malloc.h |  8 ++++++++
>  2 files changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/common/mlx5/mlx5_malloc.c
> b/drivers/common/mlx5/mlx5_malloc.c
> index 316305d..4489971 100644
> --- a/drivers/common/mlx5/mlx5_malloc.c
> +++ b/drivers/common/mlx5/mlx5_malloc.c
> @@ -151,9 +151,14 @@ static void *
>  mlx5_alloc_align(size_t size, unsigned int align, unsigned int zero)
>  {
>       void *buf;
> -     buf = memalign(align, size);
> -     if (!buf) {
> -             DRV_LOG(ERR, "Couldn't allocate buf.\n");
> +     int ret;
> +
> +     ret = posix_memalign(&buf, align, size);
> +     if (ret) {
> +             DRV_LOG(ERR,
> +                     "Couldn't allocate buf size=%zu align=%u. Err=%d\n",
> +                     size, align, ret);
> +
>               return NULL;
>       }
>       if (zero)
> @@ -190,7 +195,7 @@ mlx5_malloc(uint32_t flags, size_t size, unsigned int
> align, int socket)
>               return addr;
>       }
>       /* The memory will be allocated from system. */
> -     if (align)
> +     if (align > MLX5_MALLOC_ALIGNMENT)
>               addr = mlx5_alloc_align(size, align, !!(flags &
> MLX5_MEM_ZERO));
>       else if (flags & MLX5_MEM_ZERO)
>               addr = calloc(1, size);
> diff --git a/drivers/common/mlx5/mlx5_malloc.h
> b/drivers/common/mlx5/mlx5_malloc.h
> index d3e5f5b..8aea414 100644
> --- a/drivers/common/mlx5/mlx5_malloc.h
> +++ b/drivers/common/mlx5/mlx5_malloc.h
> @@ -9,6 +9,14 @@
>  extern "C" {
>  #endif
> 
> +#ifndef MLX5_MALLOC_ALIGNMENT
> +#ifndef RTE_ARCH_64
> +#define MLX5_MALLOC_ALIGNMENT 8
> +#else
> +#define MLX5_MALLOC_ALIGNMENT 16
> +#endif
> +#endif
> +
>  enum mlx5_mem_flags {
>       MLX5_MEM_ANY = 0,
>       /* Memory will be allocated dpends on sys_mem_en. */
> --
> 2.8.4

Patch applied to next-net-mlx,

Kindest regards,
Raslan Darawsheh