Re: [dpdk-dev] [PATCH] log: do not drop debug logs at compile time

[David Marchand <david.marchand@6wind.com>]

On Fri, Sep 16, 2016 at 9:43 AM, Olivier Matz <olivier.matz@6wind.com> wrote:
> Today, all logs whose level is lower than INFO are dropped at
> compile-time. This prevents from enabling debug logs at runtime using
> --log-level=8.
>
> The rationale was to remove debug logs from the data path at
> compile-time, avoiding a test at run-time.
>
> This patch changes the behavior of RTE_LOG() to avoid the compile-time
> optimization, and introduces the RTE_LOG_DP() macro that has the same
> behavior than the previous RTE_LOG(), for the rare cases where debug
> logs are in the data path.
>
> So it is now possible to enable debug logs at run-time by just
> specifying --log-level=8. Some drivers still have special compile-time
> options to enable more debug log. Maintainers may consider to
> remove/reduce them.
>
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
>  config/common_base                      |  1 +
>  doc/guides/faq/faq.rst                  |  2 +-
>  drivers/net/bnxt/bnxt_txr.c             |  2 +-
>  drivers/net/nfp/nfp_net.c               |  8 +++---
>  examples/distributor/main.c             |  4 +--
>  examples/ipsec-secgw/esp.c              |  2 +-
>  examples/ipsec-secgw/ipsec.c            |  4 +--
>  examples/packet_ordering/main.c         |  6 ++--
>  examples/quota_watermark/qw/main.c      |  2 +-
>  examples/tep_termination/main.c         |  4 +--
>  examples/vhost/main.c                   | 14 +++++-----
>  examples/vhost_xen/main.c               | 20 +++++++-------
>  lib/librte_eal/common/include/rte_log.h | 49 +++++++++++++++++++++------------
>  13 files changed, 67 insertions(+), 51 deletions(-)
>
> diff --git a/config/common_base b/config/common_base
> index 7830535..04b71e9 100644
> --- a/config/common_base
> +++ b/config/common_base
> @@ -89,6 +89,7 @@ CONFIG_RTE_MAX_MEMSEG=256
>  CONFIG_RTE_MAX_MEMZONE=2560
>  CONFIG_RTE_MAX_TAILQ=32
>  CONFIG_RTE_LOG_LEVEL=RTE_LOG_INFO
> +CONFIG_RTE_LOG_DP_LEVEL=RTE_LOG_INFO
>  CONFIG_RTE_LOG_HISTORY=256
>  CONFIG_RTE_LIBEAL_USE_HPET=n
>  CONFIG_RTE_EAL_ALLOW_INV_SOCKET_ID=n

[snip]

> diff --git a/lib/librte_eal/common/include/rte_log.h b/lib/librte_eal/common/include/rte_log.h
> index 919563c..76b198f 100644
> --- a/lib/librte_eal/common/include/rte_log.h
> +++ b/lib/librte_eal/common/include/rte_log.h

[snip]

> @@ -266,6 +257,30 @@ int rte_vlog(uint32_t level, uint32_t logtype, const char *format, va_list ap)
>   *   - Negative on error.
>   */
>  #define RTE_LOG(l, t, ...)                                     \
> +        rte_log(RTE_LOG_ ## l,                                 \
> +                RTE_LOGTYPE_ ## t, # t ": " __VA_ARGS__)
> +
> +/**
> + * Generates a log message for data path.
> + *
> + * Similar to RTE_LOG(), except that it is removed at compilation time
> + * if the RTE_LOG_DP_LEVEL configuration option is lower than the log
> + * level argument.
> + *
> + * @param l
> + *   Log level. A value between EMERG (1) and DEBUG (8). The short name is
> + *   expanded by the macro, so it cannot be an integer value.
> + * @param t
> + *   The log type, for example, EAL. The short name is expanded by the
> + *   macro, so it cannot be an integer value.
> + * @param ...
> + *   The fmt string, as in printf(3), followed by the variable arguments
> + *   required by the format.
> + * @return
> + *   - 0: Success.
> + *   - Negative on error.
> + */
> +#define RTE_LOG_DP(l, t, ...)                                  \
>         (void)((RTE_LOG_ ## l <= RTE_LOG_LEVEL) ?               \
>          rte_log(RTE_LOG_ ## l,                                 \
>                  RTE_LOGTYPE_ ## t, # t ": " __VA_ARGS__) :     \
> --
> 2.8.1

Hum, I suppose RTE_LOG_DP should look at RTE_LOG_DP_LEVEL.


-- 
David Marchand