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Date: Tue, 24 May 2022 07:51:05 -0700
From: Stephen Hemminger <stephen@networkplumber.org>
To: Tyler Retzlaff <roretzla@linux.microsoft.com>
Cc: dev@dpdk.org, thomas@monjalon.net, dmitry.kozliuk@gmail.com,
anatoly.burakov@intel.com, Narcisa Vasile <navasile@linux.microsoft.com>
Subject: Re: [PATCH v3 1/2] eal: get/set thread priority per thread identifier
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On Tue, 24 May 2022 04:08:36 -0700
Tyler Retzlaff <roretzla@linux.microsoft.com> wrote:
> +static int
> +thread_map_priority_to_os_value(enum rte_thread_priority eal_pri,
> + int *os_pri, int *pol)
> +{
> + /* Clear the output parameters */
> + *os_pri = sched_get_priority_min(SCHED_OTHER) - 1;
> + *pol = -1;
> +
> + switch (eal_pri) {
> + case RTE_THREAD_PRIORITY_NORMAL:
> + *pol = SCHED_OTHER;
> +
> + /*
> + * Choose the middle of the range to represent
> + * the priority 'normal'.
> + * On Linux, this should be 0, since both
> + * sched_get_priority_min/_max return 0 for SCHED_OTHER.
> + */
> + *os_pri = (sched_get_priority_min(SCHED_OTHER) +
> + sched_get_priority_max(SCHED_OTHER))/2;
> + break;
> + case RTE_THREAD_PRIORITY_REALTIME_CRITICAL:
> + *pol = SCHED_RR;
> + *os_pri = sched_get_priority_max(SCHED_RR);
> + break;
Many people have experimented with realtime priorities with DPDK
and Linux, and have never heard of any one not having problems.
Recommend that this either be an error add a warning log message
that "Setting real time priority may break"
> + default:
> + RTE_LOG(DEBUG, EAL, "The requested priority value is invalid.\n");
> + return EINVAL;
> + }
> + return 0;
> +}