Re: [PATCH v6] eal: add build-time option to omit trace

[Jerin Jacob <jerinjacobk@gmail.com>]

On Sun, Oct 6, 2024 at 7:44 PM Morten Brørup <mb@smartsharesystems.com> wrote:
>
> Some applications want to omit the trace feature.
> Either to reduce the memory footprint, to reduce the exposed attack
> surface, or for other reasons.
>
> This patch adds an option in rte_config.h to include or omit trace in the
> build. Trace is included by default.
>
> Omitting trace works by omitting all trace points.
> For API and ABI compatibility, the trace feature itself remains.
>
> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> ---
> v6:
>   Removed test_trace_perf.c changes; they don't compile for Windows
>   target, and are superfluous.
> v5:
>   Added public function rte_trace_feature_is_enabled(), to test if trace
>   is build time enabled in both the DPDK and the application. Use in test
>   application instead of private function. (Jerin Jacob)
> v4:
> * Added check for generic trace enabled when registering trace points, in
>   RTE_INIT. (Jerin Jacob)
> * Test application uses function instead of macro to check if generic
>   trace is enabled. (Jerin Jacob)
> * Performance test application uses function to check if generic trace is
>   enabled.
> v3:
> * Simpler version with much fewer ifdefs. (Jerin Jacob)
> v2:
> * Added/modified macros required for building applications with trace
>   omitted.
> ---
>  app/test/test_trace.c                      |  4 +++
>  config/rte_config.h                        |  1 +
>  lib/eal/common/eal_common_trace.c          | 10 +++++++
>  lib/eal/include/rte_trace.h                | 33 ++++++++++++++++++++++
>  lib/eal/include/rte_trace_point.h          | 21 ++++++++++++++
>  lib/eal/include/rte_trace_point_register.h |  2 ++
>  lib/eal/version.map                        |  3 ++
>  7 files changed, 74 insertions(+)
>
> diff --git a/app/test/test_trace.c b/app/test/test_trace.c
> index 00809f433b..8ea1443044 100644
> --- a/app/test/test_trace.c
> +++ b/app/test/test_trace.c
> @@ -245,6 +245,10 @@ static struct unit_test_suite trace_tests = {
>  static int
>  test_trace(void)
>  {
> +       if (!rte_trace_feature_is_enabled()) {
> +               printf("Trace omitted at build-time, skipping test\n");
> +               return TEST_SKIPPED;
> +       }
>         return unit_test_suite_runner(&trace_tests);
>  }
>
> diff --git a/config/rte_config.h b/config/rte_config.h
> index dd7bb0d35b..fd6f8a2f1a 100644
> --- a/config/rte_config.h
> +++ b/config/rte_config.h
> @@ -49,6 +49,7 @@
>  #define RTE_MAX_TAILQ 32
>  #define RTE_LOG_DP_LEVEL RTE_LOG_INFO
>  #define RTE_MAX_VFIO_CONTAINERS 64
> +#define RTE_TRACE 1
>
>  /* bsd module defines */
>  #define RTE_CONTIGMEM_MAX_NUM_BUFS 64
> diff --git a/lib/eal/common/eal_common_trace.c b/lib/eal/common/eal_common_trace.c
> index 918f49bf4f..06130c756d 100644
> --- a/lib/eal/common/eal_common_trace.c
> +++ b/lib/eal/common/eal_common_trace.c
> @@ -100,6 +100,16 @@ rte_trace_is_enabled(void)
>         return rte_atomic_load_explicit(&trace.status, rte_memory_order_acquire) != 0;
>  }
>
> +bool
> +__rte_trace_feature_is_enabled(void)
> +{
> +#ifdef RTE_TRACE
> +       return true;
> +#else
> +       return false;
> +#endif
> +}
> +static __rte_always_inline
> +bool rte_trace_feature_is_enabled(void)
> +{
> +#ifdef RTE_TRACE
> +       return __rte_trace_feature_is_enabled();
> +#else
> +       return false;
> +#endif
> +}
> +__rte_experimental
> +static __rte_always_inline bool
> +__rte_trace_point_generic_is_enabled(void)
> +{
> +#ifdef RTE_TRACE
> +       return true;
> +#else
> +       return false;
> +#endif

__rte_trace_feature_is_enabled(), rte_trace_feature_is_enabled(),
__rte_trace_point_generic_is_enabled() are duplicates.
There is no harm in using a public API inside the implementation.
Please keep only rte_trace_feature_is_enabled()
and use it across implementation and app/test.

> +}
> +
>  /**
>   * @internal
>   *

>         rte_vfio_get_device_info; # WINDOWS_NO_EXPORT
> +
> +       # added in 24.11
> +       __rte_trace_feature_is_enabled;

rte_trace_feature_is_enabled;

With the above changes,

Acked-by: Jerin Jacob <jerinj@marvell.com>



>  };
>
>  INTERNAL {
> --
> 2.43.0
>