Re: [dpdk-dev] [PATCH v9 3/3] eal/stack: enable lock-free stack for aarch64

[David Marchand <david.marchand@redhat.com>]

On Wed, Aug 14, 2019 at 10:30 AM Phil Yang <phil.yang@arm.com> wrote:
>
> Enable both c11 atomic and non c11 atomic lock-free stack for aarch64.
>
> Introduced a new header to reduce the ifdef clutter across generic and c11
> files. The rte_stack_lf_stubs.h contains stub implementations of
> __rte_stack_lf_count, __rte_stack_lf_push_elems and
> __rte_stack_lf_pop_elems.
>
> Suggested-by: Gage Eads <gage.eads@intel.com>
> Suggested-by: Jerin Jacob <jerinj@marvell.com>
> Signed-off-by: Phil Yang <phil.yang@arm.com>
> Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> Tested-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> Acked-by: Jerin Jacob <jerinj@marvell.com>
> ---
>  doc/guides/prog_guide/env_abstraction_layer.rst |  4 +--
>  doc/guides/rel_notes/release_19_11.rst          |  3 ++
>  lib/librte_stack/Makefile                       |  3 +-
>  lib/librte_stack/rte_stack_lf.h                 |  4 +++
>  lib/librte_stack/rte_stack_lf_c11.h             | 16 ---------
>  lib/librte_stack/rte_stack_lf_generic.h         | 16 ---------
>  lib/librte_stack/rte_stack_lf_stubs.h           | 44 +++++++++++++++++++++++++
>  7 files changed, 55 insertions(+), 35 deletions(-)
>  create mode 100644 lib/librte_stack/rte_stack_lf_stubs.h
>
> diff --git a/doc/guides/prog_guide/env_abstraction_layer.rst b/doc/guides/prog_guide/env_abstraction_layer.rst
> index 94f30fd..6e59fae 100644
> --- a/doc/guides/prog_guide/env_abstraction_layer.rst
> +++ b/doc/guides/prog_guide/env_abstraction_layer.rst
> @@ -648,8 +648,8 @@ Known Issues
>    Alternatively, applications can use the lock-free stack mempool handler. When
>    considering this handler, note that:
>
> -  - It is currently limited to the x86_64 platform, because it uses an
> -    instruction (16-byte compare-and-swap) that is not yet available on other
> +  - It is currently limited to the aarch64 and x86_64 platforms, because it uses
> +    an instruction (16-byte compare-and-swap) that is not yet available on other
>      platforms.
>    - It has worse average-case performance than the non-preemptive rte_ring, but
>      software caching (e.g. the mempool cache) can mitigate this by reducing the
> diff --git a/doc/guides/rel_notes/release_19_11.rst b/doc/guides/rel_notes/release_19_11.rst
> index 8490d89..60ffd70 100644
> --- a/doc/guides/rel_notes/release_19_11.rst
> +++ b/doc/guides/rel_notes/release_19_11.rst
> @@ -56,6 +56,9 @@ New Features
>       Also, make sure to start the actual text at the margin.
>       =========================================================
>
> +* **Added Lock-free Stack for aarch64.**
> +
> +  The lock-free stack implementation is enabled for aarch64 platforms.
>
>  Removed Items
>  -------------
> diff --git a/lib/librte_stack/Makefile b/lib/librte_stack/Makefile
> index 8d18ce5..c337ab7 100644
> --- a/lib/librte_stack/Makefile
> +++ b/lib/librte_stack/Makefile
> @@ -24,6 +24,7 @@ SYMLINK-$(CONFIG_RTE_LIBRTE_STACK)-include := rte_stack.h \
>                                               rte_stack_std.h \
>                                               rte_stack_lf.h \
>                                               rte_stack_lf_generic.h \
> -                                             rte_stack_lf_c11.h
> +                                             rte_stack_lf_c11.h \
> +                                                 rte_stack_lf_stubs.h

Please, use the same indentation type than the other lines.


>
>  include $(RTE_SDK)/mk/rte.lib.mk
> diff --git a/lib/librte_stack/rte_stack_lf.h b/lib/librte_stack/rte_stack_lf.h
> index f5581f0..e67630c 100644
> --- a/lib/librte_stack/rte_stack_lf.h
> +++ b/lib/librte_stack/rte_stack_lf.h
> @@ -5,11 +5,15 @@
>  #ifndef _RTE_STACK_LF_H_
>  #define _RTE_STACK_LF_H_
>
> +#if !(defined(RTE_ARCH_X86_64) || defined(RTE_ARCH_ARM64))
> +#include "rte_stack_lf_stubs.h"
> +#else
>  #ifdef RTE_USE_C11_MEM_MODEL
>  #include "rte_stack_lf_c11.h"
>  #else
>  #include "rte_stack_lf_generic.h"
>  #endif
> +#endif
>
>  /**
>   * @internal Push several objects on the lock-free stack (MT-safe).
> diff --git a/lib/librte_stack/rte_stack_lf_c11.h b/lib/librte_stack/rte_stack_lf_c11.h
> index 3d677ae..999359f 100644
> --- a/lib/librte_stack/rte_stack_lf_c11.h
> +++ b/lib/librte_stack/rte_stack_lf_c11.h
> @@ -36,12 +36,6 @@ __rte_stack_lf_push_elems(struct rte_stack_lf_list *list,
>                           struct rte_stack_lf_elem *last,
>                           unsigned int num)
>  {
> -#ifndef RTE_ARCH_X86_64
> -       RTE_SET_USED(first);
> -       RTE_SET_USED(last);
> -       RTE_SET_USED(list);
> -       RTE_SET_USED(num);
> -#else
>         struct rte_stack_lf_head old_head;
>         int success;
>
> @@ -79,7 +73,6 @@ __rte_stack_lf_push_elems(struct rte_stack_lf_list *list,
>          * to the LIFO len update.
>          */
>         __atomic_add_fetch(&list->len, num, __ATOMIC_RELEASE);
> -#endif
>  }
>
>  static __rte_always_inline struct rte_stack_lf_elem *
> @@ -88,14 +81,6 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
>                          void **obj_table,
>                          struct rte_stack_lf_elem **last)
>  {
> -#ifndef RTE_ARCH_X86_64
> -       RTE_SET_USED(obj_table);
> -       RTE_SET_USED(last);
> -       RTE_SET_USED(list);
> -       RTE_SET_USED(num);
> -
> -       return NULL;
> -#else
>         struct rte_stack_lf_head old_head;
>         uint64_t len;
>         int success;
> @@ -169,7 +154,6 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
>         } while (success == 0);
>
>         return old_head.top;
> -#endif
>  }
>
>  #endif /* _RTE_STACK_LF_C11_H_ */
> diff --git a/lib/librte_stack/rte_stack_lf_generic.h b/lib/librte_stack/rte_stack_lf_generic.h
> index 3182151..3abbb53 100644
> --- a/lib/librte_stack/rte_stack_lf_generic.h
> +++ b/lib/librte_stack/rte_stack_lf_generic.h
> @@ -36,12 +36,6 @@ __rte_stack_lf_push_elems(struct rte_stack_lf_list *list,
>                           struct rte_stack_lf_elem *last,
>                           unsigned int num)
>  {
> -#ifndef RTE_ARCH_X86_64
> -       RTE_SET_USED(first);
> -       RTE_SET_USED(last);
> -       RTE_SET_USED(list);
> -       RTE_SET_USED(num);
> -#else
>         struct rte_stack_lf_head old_head;
>         int success;
>
> @@ -75,7 +69,6 @@ __rte_stack_lf_push_elems(struct rte_stack_lf_list *list,
>         } while (success == 0);
>
>         rte_atomic64_add((rte_atomic64_t *)&list->len, num);
> -#endif
>  }
>
>  static __rte_always_inline struct rte_stack_lf_elem *
> @@ -84,14 +77,6 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
>                          void **obj_table,
>                          struct rte_stack_lf_elem **last)
>  {
> -#ifndef RTE_ARCH_X86_64
> -       RTE_SET_USED(obj_table);
> -       RTE_SET_USED(last);
> -       RTE_SET_USED(list);
> -       RTE_SET_USED(num);
> -
> -       return NULL;
> -#else
>         struct rte_stack_lf_head old_head;
>         int success;
>
> @@ -159,7 +144,6 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
>         } while (success == 0);
>
>         return old_head.top;
> -#endif
>  }
>
>  #endif /* _RTE_STACK_LF_GENERIC_H_ */
> diff --git a/lib/librte_stack/rte_stack_lf_stubs.h b/lib/librte_stack/rte_stack_lf_stubs.h
> new file mode 100644
> index 0000000..a05abf1
> --- /dev/null
> +++ b/lib/librte_stack/rte_stack_lf_stubs.h
> @@ -0,0 +1,44 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2019 Arm Limited
> + */
> +
> +#ifndef _RTE_STACK_LF_STUBS_H_
> +#define _RTE_STACK_LF_STUBS_H_
> +
> +#include <rte_common.h>
> +
> +static __rte_always_inline unsigned int
> +__rte_stack_lf_count(struct rte_stack *s)
> +{
> +       RTE_SET_USED(s);
> +
> +       return 0;
> +}
> +
> +static __rte_always_inline void
> +__rte_stack_lf_push_elems(struct rte_stack_lf_list *list,
> +                         struct rte_stack_lf_elem *first,
> +                         struct rte_stack_lf_elem *last,
> +                         unsigned int num)
> +{
> +       RTE_SET_USED(first);
> +       RTE_SET_USED(last);
> +       RTE_SET_USED(list);
> +       RTE_SET_USED(num);
> +}
> +
> +static __rte_always_inline struct rte_stack_lf_elem *
> +__rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
> +                        unsigned int num,
> +                        void **obj_table,
> +                        struct rte_stack_lf_elem **last)
> +{
> +       RTE_SET_USED(obj_table);
> +       RTE_SET_USED(last);
> +       RTE_SET_USED(list);
> +       RTE_SET_USED(num);
> +
> +       return NULL;
> +}
> +
> +#endif /* _RTE_STACK_LF_STUBS_H_ */
> --
> 2.7.4
>