Re: [PATCH v2] eal/linux: enhanced error handling for affinity

[Tyler Retzlaff <roretzla@linux.microsoft.com>]

On Thu, Apr 25, 2024 at 07:11:30PM +0800, Jianyue Wu wrote:
> From: Jianyue Wu <jianyue.wu@nokia-sbell.com>
> 
> Improve the robustness of setting thread affinity in DPDK
> by adding detailed error logging.
> 
> Changes:
> 1. Check the return value of pthread_setaffinity_np() and log an error
> if the call fails.
> 2. Include the current thread name, the intended CPU set, and a detailed
> error message in the log.
> 
> Sample prints:
> EAL: Cannot set affinity for thread dpdk-test with cpus 0,
> ret: 22, errno: 0, error description: Success
> EAL: Cannot set affinity for thread dpdk-worker1 with cpus 1,
> ret: 22, errno: 0, error description: Success
> 
> Signed-off-by: Jianyue Wu <jianyue.wu@nokia-sbell.com>
> ---
>  lib/eal/common/eal_common_thread.c |  2 +-
>  lib/eal/common/eal_thread.h        |  2 +-
>  lib/eal/unix/rte_thread.c          | 27 +++++++++++++++++++++++++--
>  3 files changed, 27 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/eal/common/eal_common_thread.c b/lib/eal/common/eal_common_thread.c
> index a53bc639ae..31a2fab2a7 100644
> --- a/lib/eal/common/eal_common_thread.c
> +++ b/lib/eal/common/eal_common_thread.c
> @@ -103,7 +103,7 @@ rte_thread_get_affinity(rte_cpuset_t *cpusetp)
>  }
>  
>  int
> -eal_thread_dump_affinity(rte_cpuset_t *cpuset, char *str, unsigned int size)
> +eal_thread_dump_affinity(const rte_cpuset_t *cpuset, char *str, unsigned int size)
>  {
>  	unsigned cpu;
>  	int ret;
> diff --git a/lib/eal/common/eal_thread.h b/lib/eal/common/eal_thread.h
> index 1c3c3442d3..85ab84baa5 100644
> --- a/lib/eal/common/eal_thread.h
> +++ b/lib/eal/common/eal_thread.h
> @@ -50,7 +50,7 @@ unsigned eal_cpu_socket_id(unsigned cpu_id);
>   *   0 for success, -1 if truncation happens.
>   */
>  int
> -eal_thread_dump_affinity(rte_cpuset_t *cpuset, char *str, unsigned int size);
> +eal_thread_dump_affinity(const rte_cpuset_t *cpuset, char *str, unsigned int size);

no objection to adding const

>  
>  /**
>   * Dump the current thread cpuset.
> diff --git a/lib/eal/unix/rte_thread.c b/lib/eal/unix/rte_thread.c
> index 1b4c73f58e..34ac0eabbf 100644
> --- a/lib/eal/unix/rte_thread.c
> +++ b/lib/eal/unix/rte_thread.c
> @@ -369,8 +369,31 @@ int
>  rte_thread_set_affinity_by_id(rte_thread_t thread_id,
>  		const rte_cpuset_t *cpuset)
>  {
> -	return pthread_setaffinity_np((pthread_t)thread_id.opaque_id,
> -		sizeof(*cpuset), cpuset);
> +	int ret;
> +#if defined(__linux__) && defined(_GNU_SOURCE)
> +	char cpus_str[RTE_CPU_AFFINITY_STR_LEN] = {'\0'};
> +	char thread_name[RTE_MAX_THREAD_NAME_LEN] = {'\0'};
> +	errno = 0;
> +#endif
> +
> +	ret = pthread_setaffinity_np((pthread_t)thread_id.opaque_id,
> +				sizeof(*cpuset), cpuset);
> +
> +#if defined(__linux__) && defined(_GNU_SOURCE)
> +	if (ret != 0) {
> +		if (pthread_getname_np((pthread_t)thread_id.opaque_id,
> +					thread_name, sizeof(thread_name)) != 0)
> +			EAL_LOG(ERR, "pthread_getname_np failed!");
> +		if (eal_thread_dump_affinity(cpuset, cpus_str, RTE_CPU_AFFINITY_STR_LEN) != 0)
> +			EAL_LOG(ERR, "eal_thread_dump_affinity failed!");
> +		EAL_LOG(ERR, "Cannot set affinity for thread %s with cpus %s, "
> +			"ret: %d, errno: %d, error description: %s",
> +			thread_name, cpus_str,
> +			ret, errno, strerror(errno));
> +	}
> +#endif
> +
> +	return ret;
>  }
>  
>  int
> -- 

i do not think introducing os specific behavior/logging to the EAL
is a good idea. logging although not formally part of the api surface
should present the same experience for all platforms. the EAL should
have a higher standard here.

> 2.34.1