Hello Robin,
On Thu, Feb 2, 2023 at 2:44 PM Robin Jarry <rja...@redhat.com> wrote:
>
> Allow applications to register a callback that will be invoked in
> rte_lcore_dump() and when requesting lcore info in the telemetry API.
>
> The callback is expected to return the number of TSC cycles that have
> passed since application start and the number of these cycles that were
> spent doing busy work.
>
> Signed-off-by: Robin Jarry <rja...@redhat.com>
> Acked-by: Morten Brørup <m...@smartsharesystems.com>
> Reviewed-by: Kevin Laatz <kevin.la...@intel.com>
> ---
>
> Notes:
> v7 -> v8: no change
>
> doc/guides/rel_notes/release_23_03.rst | 7 ++++
> lib/eal/common/eal_common_lcore.c | 48 ++++++++++++++++++++++++--
> lib/eal/include/rte_lcore.h | 35 +++++++++++++++++++
> lib/eal/version.map | 1 +
> 4 files changed, 89 insertions(+), 2 deletions(-)
>
> diff --git a/doc/guides/rel_notes/release_23_03.rst
> b/doc/guides/rel_notes/release_23_03.rst
> index 73f5d94e143d..f407dc3df7a8 100644
> --- a/doc/guides/rel_notes/release_23_03.rst
> +++ b/doc/guides/rel_notes/release_23_03.rst
> @@ -78,6 +78,13 @@ New Features
> ``rte_event_dev_config::nb_single_link_event_port_queues`` parameter
> required for eth_rx, eth_tx, crypto and timer eventdev adapters.
>
> +* **Added support for reporting lcore usage in applications.**
> +
> + * The ``/eal/lcore/list`` and ``/eal/lcore/info`` telemetry endpoints have
> + been added to provide information similar to ``rte_lcore_dump()``.
> + * Applications can register a callback at startup via
> + ``rte_lcore_register_usage_cb()`` to provide lcore usage information.
> +
EAL updates come first in RN sections.
>
> Removed Items
> -------------
> diff --git a/lib/eal/common/eal_common_lcore.c
> b/lib/eal/common/eal_common_lcore.c
> index f53fc17b4d04..bbb734098b42 100644
> --- a/lib/eal/common/eal_common_lcore.c
> +++ b/lib/eal/common/eal_common_lcore.c
> @@ -2,6 +2,7 @@
> * Copyright(c) 2010-2014 Intel Corporation
> */
>
> +#include <inttypes.h>
> #include <stdlib.h>
> #include <string.h>
>
> @@ -437,20 +438,49 @@ lcore_role_str(enum rte_lcore_role_t role)
> }
> }
>
> +static rte_lcore_usage_cb lcore_usage_cb;
> +
> +void
> +rte_lcore_register_usage_cb(rte_lcore_usage_cb cb)
> +{
> + lcore_usage_cb = cb;
> +}
> +
> static int
> lcore_dump_cb(unsigned int lcore_id, void *arg)
> {
> struct rte_config *cfg = rte_eal_get_configuration();
> char cpuset[RTE_CPU_AFFINITY_STR_LEN];
> + struct rte_lcore_usage usage;
> + rte_lcore_usage_cb usage_cb;
> + char *usage_str = NULL;
> FILE *f = arg;
> int ret;
>
> + /* The callback may not set all the fields in the structure, so clear
> it here. */
> + memset(&usage, 0, sizeof(usage));
> + /*
> + * Guard against concurrent modification of lcore_usage_cb.
> + * rte_lcore_register_usage_cb() should only be called once at
> application init
> + * but nothing prevents and application to reset the callback to NULL.
This is copy/paste a few times, only commenting here:
"prevents an* application from* resetting* the callback to NULL"
> + */
> + usage_cb = lcore_usage_cb;
> + if (usage_cb != NULL && usage_cb(lcore_id, &usage) == 0) {
> + if (asprintf(&usage_str, ", busy cycles %"PRIu64"/%"PRIu64,
> + usage.busy_cycles, usage.total_cycles) < 0) {
> + return -ENOMEM;
> + }
> + }
> ret = eal_thread_dump_affinity(&lcore_config[lcore_id].cpuset, cpuset,
> sizeof(cpuset));
> - fprintf(f, "lcore %u, socket %u, role %s, cpuset %s%s\n", lcore_id,
> + fprintf(f, "lcore %u, socket %u, role %s, cpuset %s%s%s\n", lcore_id,
> rte_lcore_to_socket_id(lcore_id),
> lcore_role_str(cfg->lcore_role[lcore_id]),
> - cpuset, ret == 0 ? "" : "...");
> + cpuset, ret == 0 ? "" : "...",
> + usage_str ? usage_str : "");
usage_str != NULL
> +
> + free(usage_str);
> +
> return 0;
> }
>
> @@ -489,7 +519,9 @@ lcore_telemetry_info_cb(unsigned int lcore_id, void *arg)
> {
> struct rte_config *cfg = rte_eal_get_configuration();
> struct lcore_telemetry_info *info = arg;
> + struct rte_lcore_usage usage;
> struct rte_tel_data *cpuset;
> + rte_lcore_usage_cb usage_cb;
> unsigned int cpu;
>
> if (info->lcore_id != lcore_id)
> @@ -508,6 +540,18 @@ lcore_telemetry_info_cb(unsigned int lcore_id, void *arg)
> rte_tel_data_add_array_int(cpuset, cpu);
> }
> rte_tel_data_add_dict_container(info->d, "cpuset", cpuset, 0);
> + /* The callback may not set all the fields in the structure, so clear
> it here. */
> + memset(&usage, 0, sizeof(usage));
> + /*
> + * Guard against concurrent modification of lcore_usage_cb.
> + * rte_lcore_register_usage_cb() should only be called once at
> application init
> + * but nothing prevents and application to reset the callback to NULL.
> + */
> + usage_cb = lcore_usage_cb;
> + if (usage_cb != NULL && usage_cb(lcore_id, &usage) == 0) {
> + rte_tel_data_add_dict_u64(info->d, "total_cycles",
> usage.total_cycles);
> + rte_tel_data_add_dict_u64(info->d, "busy_cycles",
> usage.busy_cycles);
> + }
>
> return 0;
> }
> diff --git a/lib/eal/include/rte_lcore.h b/lib/eal/include/rte_lcore.h
> index 9c7865052100..b1c8afb05d28 100644
> --- a/lib/eal/include/rte_lcore.h
> +++ b/lib/eal/include/rte_lcore.h
> @@ -328,6 +328,41 @@ typedef int (*rte_lcore_iterate_cb)(unsigned int
> lcore_id, void *arg);
> int
> rte_lcore_iterate(rte_lcore_iterate_cb cb, void *arg);
>
> +/**
> + * lcore usage statistics.
> + */
> +struct rte_lcore_usage {
> + /** The total amount of time since application start, in TSC cycles.
> */
> + uint64_t total_cycles;
This code comment needs some clarification.
What is this "total amount of time"?
"application start" is ambiguous.
EAL lcore threads are not created/started by the application itself,
so the application has no idea of the time the lcore/threads were
created.
I would describe as:
/** The total amount of time that the application has been running on
this lcore, in TSC cycles. */
Is it acceptable to you?
> + /** The amount of busy time since application start, in TSC cycles. */
> + uint64_t busy_cycles;
And here:
/** The amount of time the application was busy, handling some
workload on this lcore, in TSC cycles. */
> +};
> +
> +/**
> + * Callback to allow applications to report lcore usage.
> + *
> + * @param [in] lcore_id
> + * The lcore to consider.
> + * @param [out] usage
> + * Counters representing this lcore usage. This can never be NULL.
> + * @return
> + * - 0 if fields in usage were updated successfully. The fields that the
> + * application does not support must not be modified.
> + * - a negative value if the information is not available or if any error
> occurred.
> + */
> +typedef int (*rte_lcore_usage_cb)(unsigned int lcore_id, struct
> rte_lcore_usage *usage);
> +
> +/**
Missing a experimental banner:
* @warning
* @b EXPERIMENTAL: this API may change without prior notice.
> + * Register a callback from an application to be called in rte_lcore_dump()
> and
> + * the /eal/lcore/info telemetry endpoint handler. Applications are expected
> to
> + * report lcore usage statistics via this callback.
> + *
> + * @param cb
> + * The callback function.
> + */
> +__rte_experimental
> +void rte_lcore_register_usage_cb(rte_lcore_usage_cb cb);
> +
> /**
> * List all lcores.
> *
> diff --git a/lib/eal/version.map b/lib/eal/version.map
> index 6523102157e2..1f70caac7b9c 100644
> --- a/lib/eal/version.map
> +++ b/lib/eal/version.map
> @@ -442,6 +442,7 @@ EXPERIMENTAL {
>
> # added in 23.03
> rte_thread_set_name;
> + rte_lcore_register_usage_cb;
Alphabetical order.
> };
>
> INTERNAL {
> --
> 2.39.1
>
--
David Marchand
