pmunitsstr(3) — Linux manual page


PMUNITSSTR(3)           Library Functions Manual           PMUNITSSTR(3)

NAME         top

       pmUnitsStr, pmUnitsStr_r - convert a performance metric's units
       into a string

C SYNOPSIS         top

       #include <pcp/pmapi.h>

       const char *pmUnitsStr(const pmUnits *pu);
       char *pmUnitsStr_r(const pmUnits *pu, char *buf, int buflen);

       cc ... -lpcp

DESCRIPTION         top

       The encoding of a performance metric's dimensionality and scale
       uses a pmUnits structure; see pmLookupDesc(3).

       As an aid to labeling graphs and tables, or for error messages,
       pmUnitsStr will take a dimension and scale specification as per
       pu, and return the corresponding text string.  The pmUnitsStr_r
       function does the same, but stores the result in a user-supplied
       buffer buf of length buflen, which should have room for at least
       60 bytes.  If buflen is less than 60 then pmUnitsStr_r returns
       NULL and buf is not changed.

       For example {1, -2, 0, PM_SPACE_MBYTE, PM_TIME_SEC, 0}, as the
       value of *pu gives the result string Mbyte / sec^2.

       The string value result from pmUnitsStr is held in a single
       static buffer, so the returned value is only valid until the next
       call to pmUnitsStr.

       If the ``count'' dimension is non-zero, and the ``count'' scale
       is not zero, then the text string will include a decimal scaling
       factor, e.g.  count x 10^6.

       As a special case, if all components of the dimension are zero,
       then the ``count'' scale is used to produce the text.  If this
       scale is zero the result is an empty string, otherwise the result
       is of the form x1 0^2.

NOTES         top

       pmUnitsStr returns a pointer to a static buffer and hence is not
       thread-safe.  Multi-threaded applications should use pmUnitsStr_r

SEE ALSO         top

       PMAPI(3), pmAtomStr(3), pmConvScale(3), pmExtractValue(3),
       pmLookupDesc(3), pmPrintValue(3), pmIDStr(3), pmInDomStr(3),
       pmTypeStr(3), pmSemStr(3) and pmUnitsStr(3).

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this manual
       page, send it to  This page was obtained from the
       project's upstream Git repository
       ⟨⟩ on 2024-06-14.
       (At that time, the date of the most recent commit that was found
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       problems in this HTML version of the page, or you believe there
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       (which is not part of the original manual page), send a mail to

Performance Co-Pilot               PCP                     PMUNITSSTR(3)

Pages that refer to this page: pmlogsummary(1)pmatomstr(3)pmconvscale(3)pmextractvalue(3)pmidstr(3)pmindomstr(3)pmlookupdesc(3)pmparseunitsstr(3)pmprintvalue(3)pmsemstr(3)pmtypestr(3)pmunitsstr(3)pmwebapi(3)