---
name: "__pmLogWriteMark"
section: "3"
platform: "linux"
package: "pcp"
version: "7.2.2-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/__pmLogWriteMark"
---

# \_\_pmLogWriteMark(3)

append a \<mark\> record to a PCP archive

## NAME

**\_\_pmLogWriteMark** - append a \<mark\> record to a PCP archive

## C SYNOPSIS

**#include \<pcp/pmapi.h\>**\
 **#include \<pcp/libpcp.h\>**

**int \_\_pmLogWriteMark(\_\_pmArchCtl \****acp***,** **const \_\_pmTimestamp \****last\_stamp***,** **const \_\_pmTimestamp \****inc***);**

**cc ... -lpcp**

## CAVEAT

This documentation is intended for internal Performance Co-Pilot (PCP) developer use.

These interfaces are not part of the PCP APIs that are guaranteed to remain fixed across releases, and at some point in the future they may not work or may provide different semantics.

## DESCRIPTION

**\_\_pmLogWriteMark** appends a \<mark\> record to the current data file of a PCP archive. A \<mark\> record indicates a discontinuity in the time series of logged data in the archive, see [**PCPIntro**(1)](/PCPIntro/1.md) for more information.

The timestamp of the \<mark\> record is given by *last\_stamp* optionally incremented by *inc* unless *inc* is NULL (in which case no increment is done).

The current data volume's I/O stream and the archive version (determines the format of the \<mark\> record) are determined from **acp**.

## DIAGNOSTICS AND RETURN VALUES

The return value is 0 if all is well, else some error code less than zero that can be turned into an error message by calling [**pmErrStr**(3)](/pmErrStr/3.md).

## SEE ALSO

[**PCPIntro**(1)](/PCPIntro/1.md), [**PMAPI**(3)](/PMAPI/3.md) and **\_\_pmLogWrite**(3).