Re: [PATCH v14 1/3]: perf util: map data buffer for preserving collected data

[Song Liu <liu.song.a23@gmail.com>]

On Sun, Oct 14, 2018 at 11:44 PM Alexey Budankov
<alexey.budankov@linux.intel.com> wrote:
>
>
> The map->data buffer is used to preserve map->base profiling data
> for writing to disk. AIO map->cblock is used to queue corresponding
> map->data buffer for asynchronous writing.
>
> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>

Acked-by: Song Liu <songliubraving@fb.com>

Shall we add libaio to tools/build/Makefile.feature? It will be great to see
whether aio is enabled in "Auto-detecting system features:".

Thanks for implementing this!

Song

> ---
> Changes in v13:
>  - grouped aio functions under single #ifdef HAVE_AIO_SUPPORT
> Changes in v12:
>  - applied stub functions design for the whole patch kit
>  - grouped AIO related data into a struct under struct perf_mmap
> Changes in v10:
>  - moved specific code to perf_mmap__aio_mmap(), perf_mmap__aio_munmap()
>  - adjusted error reporting by using %m
> Changes in v9:
>   - implemented NO_AIO and HAVE_AIO_SUPPORT defines to cover cases of
>     libc implementations without Posix AIO API support
> Changes in v7:
>   - implemented handling record.aio setting from perfconfig file
>  Changes in v6:
>   - adjusted setting of priorities for cblocks;
>  Changes in v5:
>   - reshaped layout of data structures;
>   - implemented --aio option;
>  Changes in v4:
>   - converted mmap()/munmap() to malloc()/free() for mmap->data buffer management
>  Changes in v2:
>   - converted zalloc() to calloc() for allocation of mmap_aio array,
>   - cleared typo and adjusted fallback branch code;
> ---
>  tools/perf/Makefile.config |  5 +++++
>  tools/perf/Makefile.perf   |  7 ++++++-
>  tools/perf/util/evlist.c   |  2 +-
>  tools/perf/util/mmap.c     | 49 +++++++++++++++++++++++++++++++++++++++++++++-
>  tools/perf/util/mmap.h     | 11 ++++++++++-
>  5 files changed, 70 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index f6d1a03c7523..2e90f4ce9214 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -355,6 +355,11 @@ endif # NO_LIBELF
>
>  ifeq ($(feature-glibc), 1)
>    CFLAGS += -DHAVE_GLIBC_SUPPORT
> +  ifndef NO_AIO
> +    ifndef BIONIC
> +        CFLAGS += -DHAVE_AIO_SUPPORT
> +    endif
> +  endif
>  endif
>
>  ifdef NO_DWARF
> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> index 92514fb3689f..7becc6a72cf2 100644
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -97,8 +97,13 @@ include ../scripts/utilities.mak
>  # Define LIBCLANGLLVM if you DO want builtin clang and llvm support.
>  # When selected, pass LLVM_CONFIG=/path/to/llvm-config to `make' if
>  # llvm-config is not in $PATH.
> -
> +#
>  # Define NO_CORESIGHT if you do not want support for CoreSight trace decoding.
> +#
> +# Define NO_AIO if you do not want support of Posix AIO based trace
> +# streaming for record mode. Currently Posix AIO trace streaming is
> +# supported only when linking with glibc.
> +#
>
>  # As per kernel Makefile, avoid funny character set dependencies
>  unexport LC_ALL
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index be440df29615..1a83bf2c069c 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -1028,7 +1028,7 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
>          * Its value is decided by evsel's write_backward.
>          * So &mp should not be passed through const pointer.
>          */
> -       struct mmap_params mp;
> +       struct mmap_params mp = { .nr_cblocks = 0 };
>
>         if (!evlist->mmap)
>                 evlist->mmap = perf_evlist__alloc_mmap(evlist, false);
> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> index cdb95b3a1213..47cdc3ad6546 100644
> --- a/tools/perf/util/mmap.c
> +++ b/tools/perf/util/mmap.c
> @@ -153,8 +153,55 @@ void __weak auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp __mayb
>  {
>  }
>
> +#ifdef HAVE_AIO_SUPPORT
> +static int perf_mmap__aio_mmap(struct perf_mmap *map, struct mmap_params *mp)
> +{
> +       int delta_max;
> +
> +       if (mp->nr_cblocks) {
> +               map->aio.data = malloc(perf_mmap__mmap_len(map));
> +               if (!map->aio.data) {
> +                       pr_debug2("failed to allocate data buffer, error %m\n");
> +                       return -1;
> +               }
> +               /*
> +                * Use cblock.aio_fildes value different from -1
> +                * to denote started aio write operation on the
> +                * cblock so it requires explicit record__aio_sync()
> +                * call prior the cblock may be reused again.
> +                */
> +               map->aio.cblock.aio_fildes = -1;
> +               /*
> +                * Allocate cblock with max priority delta to
> +                * have faster aio write system calls.
> +                */
> +               delta_max = sysconf(_SC_AIO_PRIO_DELTA_MAX);
> +               map->aio.cblock.aio_reqprio = delta_max;
> +       }
> +
> +       return 0;
> +}
> +
> +static void perf_mmap__aio_munmap(struct perf_mmap *map)
> +{
> +       if (map->aio.data)
> +               zfree(&map->aio.data);
> +}
> +#else
> +static int perf_mmap__aio_mmap(struct perf_mmap *map __maybe_unused,
> +                              struct mmap_params *mp __maybe_unused)
> +{
> +       return 0;
> +}
> +
> +static void perf_mmap__aio_munmap(struct perf_mmap *map __maybe_unused)
> +{
> +}
> +#endif
> +
>  void perf_mmap__munmap(struct perf_mmap *map)
>  {
> +       perf_mmap__aio_munmap(map);
>         if (map->base != NULL) {
>                 munmap(map->base, perf_mmap__mmap_len(map));
>                 map->base = NULL;
> @@ -197,7 +244,7 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int c
>                                 &mp->auxtrace_mp, map->base, fd))
>                 return -1;
>
> -       return 0;
> +       return perf_mmap__aio_mmap(map, mp);
>  }
>
>  static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
> diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
> index e603314dc792..a46dbdcdcc8a 100644
> --- a/tools/perf/util/mmap.h
> +++ b/tools/perf/util/mmap.h
> @@ -6,6 +6,9 @@
>  #include <linux/types.h>
>  #include <asm/barrier.h>
>  #include <stdbool.h>
> +#ifdef HAVE_AIO_SUPPORT
> +#include <aio.h>
> +#endif
>  #include "auxtrace.h"
>  #include "event.h"
>
> @@ -26,6 +29,12 @@ struct perf_mmap {
>         bool             overwrite;
>         struct auxtrace_mmap auxtrace_mmap;
>         char             event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8);
> +#ifdef HAVE_AIO_SUPPORT
> +       struct {
> +               void             *data;
> +               struct aiocb     cblock;
> +       } aio;
> +#endif
>  };
>
>  /*
> @@ -57,7 +66,7 @@ enum bkw_mmap_state {
>  };
>
>  struct mmap_params {
> -       int                         prot, mask;
> +       int                         prot, mask, nr_cblocks;
>         struct auxtrace_mmap_params auxtrace_mp;
>  };
>