pmunitsstr(3) [centos man page]

PMUNITSSTR(3)						     Library Functions Manual						     PMUNITSSTR(3)

NAME

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

C SYNOPSIS

       #include <pcp/pmapi.h>

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

       cc ... -lpcp

DESCRIPTION

       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.

       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 pmU-
       nitsStr.

       If the ``count'' dimension is non-zero, and the ``count'' scale is not zero, then the text string will include a  decimal  scaling  factor,
       eg.  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

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

SEE ALSO

       PMAPI(3), pmAtomStr(3), pmConvScale(3), pmExtractValue(3), pmLookupDesc(3), pmPrintValue(3) and pmTypeStr(3).

Performance Co-Pilot							PCP							     PMUNITSSTR(3)

PMCONVSCALE(3)						     Library Functions Manual						    PMCONVSCALE(3)

NAME

       pmConvScale - rescale a performance metric value

C SYNOPSIS

       #include <pcp/pmapi.h>

       int pmConvScale(int type, const pmAtomValue *ival, const pmUnits *iunit, pmAtomValue *oval, const pmUnits *ounit);

       cc ... -lpcp

DESCRIPTION

       All performance metric values may be encoded in a pmAtomValue union, defined as follows;

	    typedef union {
		__int32_t    l;     /* 32-bit signed */
		__uint32_t   ul;    /* 32-bit unsigned */
		__int64_t    ll;    /* 64-bit signed */
		__uint64_t   ull;   /* 64-bit unsigned */
		float	     f;     /* 32-bit floating point */
		double	     d;     /* 64-bit floating point */
		char	     *cp;   /* char ptr */
		pmValueBlock *vbp;  /* pmValueBlock ptr */
	    } pmAtomValue;

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

       Given  a  performance  metric value pointed to by ival multiply it by a scale factor and return the value in oval.  The scaling takes place
       from the units defined by iunit into the units defined by ounit.  Both input and output units must have the same dimensionality.

       The performance metric type for both input and output values is determined by type, the value for which is typically extracted from a pmDe-
       sc structure, following a call to pmLookupDesc(3) for a particular performance metric.

       pmConvScale is most useful when values returned via pmFetch(3), (and possibly extracted using pmExtractValue(3)) need to be normalized into
       some canonical scale and units for the purposes of computation.

       As a special case, if all components of the dimension are zero, then this is treated as synonymous with a ``count'' dimension of  one,  and
       so  the ``count'' scale components determine the relative scaling.  This accommodates the case where performance metrics are dimensionless,
       without special case handling on the part of the caller.

SEE ALSO

       PMAPI(3), pmAtomStr(3), pmExtractValue(3), pmFetch(3), pmLookupDesc(3), pmPrintValue(3), pmTypeStr(3) and pmUnitsStr(3).

DIAGNOSTICS

       PM_ERR_CONV

	      iunit and ounit have different dimensionality, or have inappropriate type

       PM_ERR_UNIT

	      Inappropriate iunit or ounit parameter

Performance Co-Pilot							PCP							    PMCONVSCALE(3)