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SubjectRe: [PATCH v9 1/3]: perf util: map data buffer for preserving collected data
On Wed, Oct 03, 2018 at 07:01:26PM +0300, Alexey Budankov 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>
> ---
> 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 | 4 +++-
> tools/perf/util/mmap.c | 31 +++++++++++++++++++++++++++++++
> tools/perf/util/mmap.h | 11 +++++++++++
> 5 files changed, 56 insertions(+), 2 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..af2f8c965d7a 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -1029,7 +1029,9 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
> * So &mp should not be passed through const pointer.
> */
> struct mmap_params mp;
> -
> +#ifdef HAVE_AIO_SUPPORT
> + mp.nr_cblocks = 0;
> +#endif
> if (!evlist->mmap)
> evlist->mmap = perf_evlist__alloc_mmap(evlist, false);
> if (!evlist->mmap)
> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> index cdb95b3a1213..5b3727b0c7c0 100644
> --- a/tools/perf/util/mmap.c
> +++ b/tools/perf/util/mmap.c
> @@ -155,6 +155,10 @@ void __weak auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp __mayb
>
> void perf_mmap__munmap(struct perf_mmap *map)
> {
> +#ifdef HAVE_AIO_SUPPORT
> + if (map->data)
> + zfree(&map->data);
> +#endif
> if (map->base != NULL) {
> munmap(map->base, perf_mmap__mmap_len(map));
> map->base = NULL;
> @@ -166,6 +170,9 @@ void perf_mmap__munmap(struct perf_mmap *map)
>
> int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int cpu)
> {
> +#ifdef HAVE_AIO_SUPPORT
> + int delta_max;
> +#endif
> /*
> * The last one will be done at perf_mmap__consume(), so that we
> * make sure we don't prevent tools from consuming every last event in
> @@ -190,6 +197,30 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int c
> map->base = NULL;
> return -1;
> }
> +#ifdef HAVE_AIO_SUPPORT
> + map->nr_cblocks = mp->nr_cblocks;
> + if (map->nr_cblocks) {
> + map->data = malloc(perf_mmap__mmap_len(map));
> + if (!map->data) {
> + pr_debug2("failed to allocate data buffer, error %d\n",
> + errno);

I guess the error code is not very useful than the message. But in
this case it's probably ENOMEM so we can simply omit it.


> + 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->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->cblock.aio_reqprio = delta_max;
> + }
> +#endif

What about separating this part into a function with the #ifdef.
Providing a dummy function when not defined would make the code
cleaner IMHO. You may consider adding util/aio.[ch].

Thanks,
Namhyung


> map->fd = fd;
> map->cpu = cpu;
>
> diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
> index e603314dc792..1b63b6cc7cf9 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 +29,11 @@ struct perf_mmap {
> bool overwrite;
> struct auxtrace_mmap auxtrace_mmap;
> char event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8);
> +#ifdef HAVE_AIO_SUPPORT
> + void *data;
> + struct aiocb cblock;
> + int nr_cblocks;
> +#endif
> };
>
> /*
> @@ -59,6 +67,9 @@ enum bkw_mmap_state {
> struct mmap_params {
> int prot, mask;
> struct auxtrace_mmap_params auxtrace_mp;
> +#ifdef HAVE_AIO_SUPPORT
> + int nr_cblocks;
> +#endif
> };
>
> int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int cpu);

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