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Thu, 26 Jan 2023 03:22:20 -0800 (PST) X-Google-Smtp-Source: AMrXdXuLzCmE0IuXleTai1ptzWUynUk01w7u93/UNKGP4gKNPWMqljCjekvWbNMt5aGJs6kMJ9nDx8CSMdcvNwvYW+w= X-Received: by 2002:a17:906:c206:b0:78d:b819:e0e7 with SMTP id d6-20020a170906c20600b0078db819e0e7mr4166709ejz.83.1674732140528; Thu, 26 Jan 2023 03:22:20 -0800 (PST) MIME-Version: 1.0 References: <20221123102612.1688865-1-rjarry@redhat.com> <20230119150656.418404-1-rjarry@redhat.com> <20230119150656.418404-3-rjarry@redhat.com> In-Reply-To: <20230119150656.418404-3-rjarry@redhat.com> From: David Marchand Date: Thu, 26 Jan 2023 12:22:07 +0100 Message-ID: Subject: Re: [PATCH v6 2/5] eal: allow applications to report their cpu usage To: Robin Jarry Cc: dev@dpdk.org, Tyler Retzlaff , Kevin Laatz , =?UTF-8?Q?Morten_Br=C3=B8rup?= X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Thu, Jan 19, 2023 at 4:08 PM Robin Jarry 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 > Acked-by: Morten Br=C3=B8rup > --- > > Notes: > v5 -> v6: Added/rephrased some inline comments. > > lib/eal/common/eal_common_lcore.c | 45 ++++++++++++++++++++++++++++--- > lib/eal/include/rte_lcore.h | 35 ++++++++++++++++++++++++ > lib/eal/version.map | 1 + > 3 files changed, 78 insertions(+), 3 deletions(-) > > diff --git a/lib/eal/common/eal_common_lcore.c b/lib/eal/common/eal_commo= n_lcore.c > index 16548977dce8..80513cfe3725 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 > #include > #include > > @@ -422,11 +423,21 @@ rte_lcore_iterate(rte_lcore_iterate_cb cb, void *ar= g) > return ret; > } > > +static rte_lcore_usage_cb lcore_usage_cb; > + > +void > +rte_lcore_register_usage_cb(rte_lcore_usage_cb cb) > +{ > + lcore_usage_cb =3D cb; > +} > + > static int > lcore_dump_cb(unsigned int lcore_id, void *arg) > { > struct rte_config *cfg =3D rte_eal_get_configuration(); > - char cpuset[RTE_CPU_AFFINITY_STR_LEN]; > + char cpuset[RTE_CPU_AFFINITY_STR_LEN], usage_str[256]; This is a debug/non performance sensitive helper. Please remove this "big enough for now" buffer and use a dynamic allocation= . > + struct rte_lcore_usage usage; > + rte_lcore_usage_cb usage_cb; > const char *role; > FILE *f =3D arg; > int ret; > @@ -446,11 +457,25 @@ lcore_dump_cb(unsigned int lcore_id, void *arg) > break; > } > > + /* The callback may not set all the fields in the structure, so c= lear it here. */ > + memset(&usage, 0, sizeof(usage)); > + usage_str[0] =3D '\0'; > + /* > + * Guard against concurrent modification of lcore_usage_cb. > + * rte_lcore_register_usage_cb() should only be called once at ap= plication init > + * but nothing prevents and application to reset the callback to = NULL. > + */ > + usage_cb =3D lcore_usage_cb; > + if (usage_cb !=3D NULL && usage_cb(lcore_id, &usage) =3D=3D 0) { > + snprintf(usage_str, sizeof(usage_str), ", busy cycles %"P= RIu64"/%"PRIu64, > + usage.busy_cycles, usage.total_cycles); > + } > ret =3D 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_i= d, > + fprintf(f, "lcore %u, socket %u, role %s, cpuset %s%s%s\n", lcore= _id, > rte_lcore_to_socket_id(lcore_id), role, cpuset, > - ret =3D=3D 0 ? "" : "..."); > + ret =3D=3D 0 ? "" : "...", usage_str); > + > return 0; > } > > @@ -489,7 +514,9 @@ lcore_telemetry_info_cb(unsigned int lcore_id, void *= arg) > { > struct lcore_telemetry_info *info =3D arg; > struct rte_config *cfg =3D rte_eal_get_configuration(); > + struct rte_lcore_usage usage; > struct rte_tel_data *cpuset; > + rte_lcore_usage_cb usage_cb; > const char *role; > unsigned int cpu; Reverse xmas tree please. > > @@ -522,6 +549,18 @@ lcore_telemetry_info_cb(unsigned int lcore_id, void = *arg) > if (CPU_ISSET(cpu, &lcore_config[lcore_id].cpuset)) > 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 c= lear 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 ap= plication init > + * but nothing prevents and application to reset the callback to = NULL. > + */ > + usage_cb =3D lcore_usage_cb; > + if (usage_cb !=3D NULL && usage_cb(lcore_id, &usage) =3D=3D 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.b= usy_cycles); > + } > > return 0; > } > diff --git a/lib/eal/include/rte_lcore.h b/lib/eal/include/rte_lcore.h > index 6938c3fd7b81..52468e7120dd 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 lco= re_id, void *arg); > int > rte_lcore_iterate(rte_lcore_iterate_cb cb, void *arg); > > +/** > + * CPU usage statistics. Let's be consistent and use lcore. > + */ > +struct rte_lcore_usage { > + uint64_t total_cycles; > + /**< The total amount of time since application start, in TSC cyc= les. */ > + uint64_t busy_cycles; > + /**< The amount of busy time since application start, in TSC cycl= es. */ This is confusing to have the comments after. Please put those comments before the associated fields (using /** ). > +}; > + > +/** > + * Callback to allow applications to report CPU usage. lcore* > + * > + * @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 t= he > + * application does not support must not be modified. > + * - a negative value if the information is not available or if any er= ror occurred. > + */ > +typedef int (*rte_lcore_usage_cb)(unsigned int lcore_id, struct rte_lcor= e_usage *usage); > + > +/** > + * Register a callback from an application to be called in rte_lcore_dum= p() and > + * the /eal/lcore/info telemetry endpoint handler. Applications are expe= cted to > + * report CPU usage statistics via this callback. lcore* > + * > + * @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 7ad12a7dc985..30fd216a12ea 100644 > --- a/lib/eal/version.map > +++ b/lib/eal/version.map > @@ -440,6 +440,7 @@ EXPERIMENTAL { > rte_thread_detach; > rte_thread_equal; > rte_thread_join; > + rte_lcore_register_usage_cb; Please start a new block for 23.03 symbols. --=20 David Marchand