NAME¶

pmgenmap - generate C code to simplify handling of performance metrics

SYNOPSIS¶

pmgenmap [infile]

DESCRIPTION¶

Given one or more lists of metric names in infile or on standard input, pmgenmap generates C declarations and cpp(1) macros suitable for use across the Performance Metrics Programming Interface (PMAPI) on standard output.

The declarations produced by pmgenmap simplify the coding for client applications using the PMAPI.

The input should consist of one or more lists of metric names of the form

listname {


    metricname1 symbolname1


    metricname2 symbolname2


    ...
}

which will generate C and cpp(1) declarations of the form

char *listname[] = {
#define symbolname1 0


    "metricname1",
#define symbolname2 1


    "metricname2",


    ...
};

The array declarations produced are suitable as parameters to pmLookupName(3) and the #defined constants may be used to index the vsets in the pmResult structure returned by a pmFetch(3) call.

Obviously, listname must conform to the C identifier naming rules, each symbolname must conform to the cpp(1) macro naming rules, and each metricname is expected to be a valid performance metrics name (see pmns(5) for more details).

The input may include sh-style comment lines, i.e. with a `#' as the first non-blank character of a line, and these are translated on output to either single line or multi-line C comments in the K&R style. For example, the input:

# leading block of multi-line comments
# initialization group
foo {


        a.b.c   ONE


        d.e.f.g TWO


        # embedded block of multi-lines


        # comments and boring pad text


        xx.yy.zz        THREE
}
# trailing single line comment

Produces the output:

/*


 * leading block of multi-line comments


 * initialization group


 */
char *foo[] = {
#define ONE 0


        "a.b.c",
#define TWO 1


        "d.e.f.g",
/*


 * embedded block of multi-lines


 * comments and boring pad text


 */
#define THREE 2


        "xx.yy.zz",
};
/* trailing single line comment */

EXAMPLE¶

For brevity we have removed the error handling code, and assumed the chosen metrics do not have multiple values.

The input file

mystats {


    kernel.percpu.cpu.idle     IDLE


    kernel.percpu.cpu.sys      SYS


    kernel.percpu.cpu.user     USER


    hinv.ncpu                       NCPU
}

produces the following C code, suitable for #include-ing

/*


 * Performance Metrics Name Space Map


 * Built by pmgenmap from the file


 * mystats.metrics


 * on Wed Dec 28 19:44:17 EST 1994


 *


 * Do not edit this file!


 */
char *mystats[] = {
#define IDLE    0


        "kernel.percpu.cpu.idle",
#define SYS     1


        "kernel.percpu.cpu.sys",
#define USER    2


        "kernel.percpu.cpu.user",
#define NCPU    3


        "hinv.ncpu",
};

Using the code generated by pmgenmap, we are now able to easily obtain metrics from the Performance Metrics Collection Subsystem (PMCS) as follows:

#define MAX_PMID 4


    int         trip = 0;


    int         numpmid = sizeof(mystats)/sizeof(mystats[0]);


    double      duration;


    pmResult    *resp;


    pmResult    *prev;


    pmID        pmidlist[MAX_PMID];


    pmNewContext(PM_CONTEXT_HOST, "localhost");


    pmLookupName(numpmid, mystats, pmidlist);


    pmFetch(numpmid, pmidlist, &resp);


    printf("%d CPUs: %d usr   %d sys   %d   idle0, 


           resp->vset[NCPU]->vlist[0].value.lval,


           resp->vset[USER]->vlist[0].value.lval,


           resp->vset[SYS]->vlist[0].value.lval,


           resp->vset[IDLE]->vlist[0].value.lval);

Some calls to ensure portability have been removed from the code above for the sake of clarity - the example above should not be used as a template for programming. In particular, the raw values of the metrics were used when pmLookupDesc(3) should have been called to determine the semantics of each metric.

More complete examples that demonstrate the use of pmgenmap which may be used as a basis for program development are included in the PCP demos, e.g. $PCP_DEMOS_DIR/pmclient.

FILES¶

$PCP_VAR_DIR/pmns/*

default PMNS specification files

PCP ENVIRONMENT¶

Environment variables with the prefix PCP_ are used to parameterize the file and directory names used by PCP. On each installation, the file /etc/pcp.conf contains the local values for these variables. The $PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5).

SEE ALSO¶

cpp(1), PMAPI(3), pmFetch(3), pmLookupName(3), pmNewContext(3), pcp.conf(5), pcp.env(5) and pmns(5).