---
name: "ibv_attach_counters_point_flow"
section: "3"
platform: "linux"
package: "rdma-core"
version: "65.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/ibv_attach_counters_point_flow"
---

# ibv\_attach\_counters\_point\_flow(3)

attach individual counter definition to a flow object

## NAME

**ibv\_attach\_counters\_point\_flow** - attach individual counter definition to a flow object

## SYNOPSIS

-

  ```
  #include <infiniband/verbs.h>
  int ibv_attach_counters_point_flow(struct ibv_counters *counters,
                                     struct ibv_counter_attach_attr *counter_attach_attr,
                                     struct ibv_flow *flow);
  ```

## DESCRIPTION

Attach counters point are a family of APIs to attach individual counter description definition to a verb object at a specific index location.

Counters object will start collecting values after it is bound to the verb object resource.

A static attach can be created when NULL is provided instead of the reference to the verbs object (e.g.: in case of flow providing NULL instead of *flow*). In this case, this counters object will only start collecting values after it is bound to the verbs resource, for flow this is when referencing the counters handle when creating a flow with **ibv\_create\_flow**().

Once an ibv\_counters is bound statically to a verbs resource, no additional attach is allowed till the counter object is not bound to any verb object.

The argument counter\_desc specifies which counter value should be collected. It is defined in verbs.h as one of the enum ibv\_counter\_description options.

Supported capabilities of specific counter\_desc values per verbs object can be tested by checking the return value for success or ENOTSUP errno.

Attaching a counters handle to multiple objects of the same type will accumulate the values into a single index. e.g.: creating several ibv\_flow(s) with the same ibv\_counters handle will collect the values from all relevant flows into the relevant index location when reading the values from **ibv\_read\_counters**(), setting the index more than once with different or same counter\_desc will aggregate the values from all relevant counters into the relevant index location.

The runtime values of counters can be read from the hardware by calling **ibv\_read\_counters**().

## ARGUMENTS

- *counters*

  Existing counters to attach new counter point on.

- *counter\_attach\_attr*

  An ibv\_counter\_attach\_attr struct, as defined in verbs.h.

- *flow*

  Existing flow to attach a new counters point on (in static mode it must be NULL).

### *counter\_attach\_attr* Argument

-

  ```
  struct ibv_counter_attach_attr {
      enum ibv_counter_description counter_desc;
      uint32_t index;
      uint32_t comp_mask;
  };
  ```

### *counter\_desc* Argument

-

  ```
  enum ibv_counter_description {
      IBV_COUNTER_PACKETS,
      IBV_COUNTER_BYTES,
  };
  ```

- *index*

  Desired location of the specific counter at the counters object.

- *comp\_mask*

  Bitmask specifying what fields in the structure are valid.

## RETURN VALUE

**ibv\_attach\_counters\_point\_flow**() returns 0 on success, or the value of errno on failure (which indicates the failure reason)

## ERRORS

- EINVAL

  invalid argument(s) passed

- ENOTSUP

  *counter\_desc* is not supported on the requested object

- EBUSY

  the counter object is already bound to a flow, additional attach calls is not allowed (valid for static attach only)

- ENOMEM

  not enough memory

## NOTES

Counter values in each index location are cleared upon creation when calling **ibv\_create\_counters**(). Attaching counters points will only increase these values accordingly.

## EXAMPLE

An example of use of **ibv\_attach\_counters\_point\_flow**() is shown in **ibv\_read\_counters**

## SEE ALSO

**ibv\_create\_counters**, **ibv\_destroy\_counters**, **ibv\_read\_counters**, **ibv\_create\_flow**

## AUTHORS

Raed Salem ⟨raeds@mellanox.com⟩\\c

Alex Rosenbaum ⟨alexr@mellanox.com⟩\\c