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.TH "ibv_read_counters" "3" "2018-04-02" "libibverbs" "Libibverbs Programmer\[cq]s Manual"
.hy
.SH NAME
.PP
\f[B]ibv_read_counters\f[R] - Read counter values
.SH SYNOPSIS
.IP
.nf
\f[C]
#include <infiniband/verbs.h>

int ibv_read_counters(struct ibv_counters *counters,
                      uint64_t *counters_value,
                      uint32_t ncounters,
                      uint32_t flags);
\f[R]
.fi
.SH DESCRIPTION
.PP
\f[B]ibv_read_counters\f[R]() returns the values of the chosen counters
into \f[I]counters_value\f[R] array of which can accumulate
\f[I]ncounters\f[R].
The values are filled according to the configuration defined by the user
in the \f[B]ibv_attach_counters_point_xxx\f[R] functions.
.SH ARGUMENTS
.TP
\f[I]counters\f[R]
Counters object to read.
.TP
\f[I]counters_value\f[R]
Input buffer to hold read result.
.TP
\f[I]ncounters\f[R]
Number of counters to fill.
.TP
\f[I]flags\f[R]
Use enum ibv_read_counters_flags.
.SS \f[I]flags\f[R] Argument
.TP
IBV_READ_COUNTERS_ATTR_PREFER_CACHED
Will prefer reading the values from driver cache, else it will do
volatile hardware access which is the default.
.SH RETURN VALUE
.PP
\f[B]ibv_read_counters\f[R]() returns 0 on success, or the value of
errno on failure (which indicates the failure reason)
.SH EXAMPLE
.PP
Example: Statically attach counters to a new flow
.PP
This example demonstrates the use of counters which are attached
statically with the creation of a new flow.
The counters are read from hardware periodically, and finally all
resources are released.
.IP
.nf
\f[C]
/* create counters object and define its counters points        */
/* create simple L2 flow with hardcoded MAC, and a count action */
/* read counters periodically, every 1sec, until loop ends      */
/* assumes user prepared a RAW_PACKET QP as input               */
/* only limited error checking in run time for code simplicity  */

#include <inttypes.h>
#include <infiniband/verbs.h>

/* the below MAC should be replaced by user */
#define FLOW_SPEC_ETH_MAC_VAL {
    .dst_mac = { 0x00, 0x01, 0x02, 0x03, 0x04,0x05},
    .src_mac = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
    .ether_type = 0, .vlan_tag = 0, }
#define FLOW_SPEC_ETH_MAC_MASK {
    .dst_mac = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
    .src_mac = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
    .ether_type = 0, .vlan_tag = 0, }

void example_create_flow_with_counters_on_raw_qp(struct ibv_qp *qp) {
    int idx = 0;
    int loop = 10;
    struct ibv_flow *flow = NULL;
    struct ibv_counters *counters = NULL;
    struct ibv_counters_init_attr init_attr = {0};
    struct ibv_counter_attach_attr attach_attr = {0};

    /* create single counters handle */
    counters = ibv_create_counters(qp->context, &init_attr);

    /* define counters points */
    attach_attr.counter_desc = IBV_COUNTER_PACKETS;
    attach_attr.index = idx++;
    ret = ibv_attach_counters_point_flow(counters, &attach_attr, NULL);
    if (ret == ENOTSUP) {
        fprintf(stderr, \[dq]Attaching IBV_COUNTER_PACKETS to flow is not \[rs]
supported\[dq]);
        exit(1);
    }
    attach_attr.counter_desc = IBV_COUNTER_BYTES;
    attach_attr.index = idx++;
    ibv_attach_counters_point_flow(counters, &attach_attr, NULL);
    if (ret == ENOTSUP) {
        fprintf(stderr, \[dq]Attaching IBV_COUNTER_BYTES to flow is not \[rs]
supported\[dq]);
        exit(1);
    }

    /* define a new flow attr that includes the counters handle */
    struct raw_eth_flow_attr {
        struct ibv_flow_attr              attr;
        struct ibv_flow_spec_eth          spec_eth;
        struct ibv_flow_spec_counter_action spec_count;
    } flow_attr = {
        .attr = {
                .comp_mask  = 0,
                .type       = IBV_FLOW_ATTR_NORMAL,
                .size       = sizeof(flow_attr),
                .priority   = 0,
                .num_of_specs = 2, /* ETH + COUNT */
                .port       = 1,
                .flags      = 0,
            },
        .spec_eth = {
                .type = IBV_EXP_FLOW_SPEC_ETH,
                .size = sizeof(struct ibv_flow_spec_eth),
                .val  = FLOW_SPEC_ETH_MAC_VAL,
                .mask = FLOW_SPEC_ETH_MAC_MASK,
            },
        .spec_count = {
                .type   = IBV_FLOW_SPEC_ACTION_COUNT,
                .size   = sizeof(struct ibv_flow_spec_counter_action),
                .counters = counters, /* attached this counters handle
to the newly created ibv_flow */ } };

    /* create the flow */
    flow = ibv_create_flow(qp, &flow_attr.attr);

    /* allocate array for counters value reading */
    uint64_t *counters_value = malloc(sizeof(uint64_t) * idx);

    /* periodical read and print of flow counters */
    while (--loop) {
        sleep(1);

        /* read hardware counters values */
        ibv_read_counters(counters, counters_value, idx,
                  IBV_READ_COUNTERS_ATTR_PREFER_CACHED);

        printf(\[dq]PACKETS = %\[dq]PRIu64\[dq], BYTES = %\[dq]PRIu64 \[rs]n\[dq],
            counters_value[0], counters_value[1] );
    }

    /* all done, release all */
    free(counters_value);

    /* destroy flow and detach counters */
    ibv_destroy_flow(flow);

    /* destroy counters handle */
    ibv_destroy_counters(counters);

    return;
}
\f[R]
.fi
.SH SEE ALSO
.PP
\f[B]ibv_create_counters\f[R], \f[B]ibv_destroy_counters\f[R],
\f[B]ibv_attach_counters_point_flow\f[R], \f[B]ibv_create_flow\f[R]
.SH AUTHORS
.PP
Raed Salem <raeds@mellanox.com>
.PP
Alex Rosenbaum <alexr@mellanox.com>