path: root/man/man1/pmie.1

'\"! tbl | mmdoc
'\"macro stdmacro
.\"
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.\"
.TH PMIE 1 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pmie\f1 \- inference engine for performance metrics
.SH SYNOPSIS
\f3pmie\f1
[\f3\-bCdefHVvWxz\f1]
[\f3\-A\f1 \f2align\f1]
[\f3\-a\f1 \f2archive\f1]
[\f3\-c\f1 \f2filename\f1]
[\f3\-h\f1 \f2host\f1]
[\f3\-l\f1 \f2logfile\f1]
[\f3\-j\f1 \f2stompfile\f1]
[\f3\-n\f1 \f2pmnsfile\f1]
[\f3\-O\f1 \f2offset\f1]
[\f3\-S\f1 \f2starttime\f1]
[\f3\-T\f1 \f2endtime\f1]
[\f3\-t\f1 \f2interval\f1]
[\f3\-U\f1 \f2username\f1]
[\f3\-Z\f1 \f2timezone\f1]
[\f2filename ...\f1]
.SH DESCRIPTION
.B pmie
accepts a collection of arithmetic, logical, and rule expressions to be
evaluated at specified frequencies.  The base data for the expressions
consists of performance metrics values delivered in real-time
from any host
running the Performance Metrics Collection Daemon (PMCD), or using historical
data from Performance Co-Pilot (PCP) archive logs.
.P
As well as computing arithmetic and logical values,
.B pmie
can execute actions (popup alarms, write system log messages, and launch 
programs) in response to specified conditions.  Such actions are
extremely useful in detecting, monitoring and correcting performance
related problems.
.P
The expressions to be evaluated are read from
configuration files specified by one or more
.I filename
arguments.  In the absence of any
.IR filename ,
expressions are read from standard input.
.P
A description of the command line options specific to
.B pmie
follows:
.TP 5
.B \-a
.I archive
is the base name of a PCP archive log written by
.BR pmlogger (1).
Multiple instances of the
.B \-a
flag may appear on the command line to specify a set of archives.
In this case, it is required that only one archive be present for any
one host.
Also, any explicit host names occurring in a
.B pmie
expression must match the host name recorded in one of the archive labels.
In the case of multiple archives, timestamps recorded in the archives are
used to ensure temporal consistency.
.TP
.B \-b
Output will be line buffered and standard output is attached to standard
error.  This is most useful for background execution in conjunction with
the
.B \-l
option.
The
.B \-b
option is always used for
.B pmie
instances launched from
.BR pmie_check (1).
.TP
.B \-C
Parse the configuration file(s) and exit before performing any evaluations.
Any errors in the configuration file are reported.
.TP
.B \-c
An alternative to specifying
.I filename
at the end of the command line.
.TP
.B \-d
Normally
.B pmie
would be launched as a non-interactive process to monitor and manage the
performance of one or more hosts.
Given the
.B \-d
flag however, execution is interactive and the user is presented
with a menu of options.
Interactive mode is useful mainly for debugging new expressions.
.TP
.B \-e
When used with
.BR \-V ,
.B \-v
or
.BR \-W ,
this option
forces timestamps to be reported with each expression.  The timestamps
are in
.BR ctime (3)
format, enclosed in parenthesis and appear after the expression name and before the
expression value, e.g.
.nf
	expr_1 (Tue Feb  6 19:55:10 2001): 12
.fi
.TP
.B \-f
If the
.B \-l
option is specified and there is no
.B \-a
option (ie. real-time monitoring) then
.B pmie
is run as a daemon in the background
(in all other cases foreground is the default).
The
.B \-f
option forces
.B pmie
to be run in the foreground, independent of any other options.
.TP
.B \-H
The default hostname written to the stats file will not be looked up via
.BR gethostbyname (3),
rather it will be written as-is.
This option can be useful when host name aliases are in use at a site,
and the logical name is more important than the physical host name.
.TP
.B \-h
By default performance data is fetched from the local host (in real-time mode)
or the host for the first named archive on the command line
(in archive mode).  The \f2host\f1 argument overrides this default.
It does not override hosts explicitly named in the expressions
being evaluated.
.TP
.B \-l
Standard error is sent to
.IR logfile .
.TP
.B \-j
An alternative STOMP protocol configuration is loaded from
.IR stompfile .
If this option is not used, and the
.I stomp
action is used in any rule, the default location
.I $PCP_SYSCONF_DIR/pmie/config/stomp
will be used.
.TP
.B \-n
An alternative Performance Metrics Name Space (PMNS) is loaded from the file
.IR pmnsfile .
.TP
.B \-t
The
.I interval
argument follows the syntax described in
.BR PCPIntro (1),
and in the simplest form may be an unsigned integer (the implied
units in this case are seconds).
The value is used to determine the sample interval for
expressions that do not explicitly set their sample interval using
the
.B pmie
variable \f(CWdelta\f1 described below.
The default is 10.0 seconds.
.TP
\f3\-U\f1 \f2username\f1
User account under which to run
.BR pmie .
The default is the current user account for interactive use.
When run as a daemon, the unprivileged "pcp" account is used
in current versions of PCP, but in older versions the superuser
account ("root") was used by default.
.TP
.B \-v
Unless one of the verbose options
.BR \-V ,
.B \-v
or
.B \-W
appears on the command line, expressions are
evaluated silently, the only output is as a result of any actions
being executed.  In the verbose mode, specified using the
.B \-v
flag, the value of each expression is printed as it is
evaluated.  
The values are in canonical units;
bytes in the dimension of ``space'', seconds in the dimension of ``time''
and events in the dimension of ``count''.
See
.BR pmLookupDesc (3)
for details of the supported dimension and scaling mechanisms
for performance metrics.
The verbose mode is useful in monitoring the value of given
expressions, evaluating derived performance metrics,
passing these values on to other tools for further processing
and in debugging new expressions.
.TP
.B \-V
This option has the same effect as the
.B \-v
option, except that the name of the host and instance
(if applicable) are printed as well as expression values.
.TP
.B \-W
This option has the same effect as the
.B \-V
option described above, except that for boolean expressions,
only those names and values that make the expression true are printed.
These are the same names and values accessible to rule actions as the
%h, %i and %v bindings, as described below.
.TP
.B \-x
Execute in domain agent mode.  This mode is used within the Performance
Co-Pilot product to derive values for summary metrics, see
.BR pmdasummary (1).
Only restricted functionality
is available in this mode
(expressions with actions may
.B not
be used).
.TP
.B \-Z
Change the reporting timezone to
.I timezone
in the format of the environment variable
.B TZ
as described in
.BR environ (5).
.TP
.B \-z
Change the reporting timezone to the timezone of the host that is the source
of the performance metrics, as identified via either the
.B \-h
option or the first named archive (as described above for the
.B \-a
option).
.P
The
.BR \-S ,
.BR \-T ,
.BR \-O ,
and
.B \-A
options may be used to define a time window to restrict the
samples retrieved, set an initial origin within the time window,
or specify a ``natural'' alignment of the sample times; refer to
.BR PCPIntro (1)
for a complete description of these options.
.P
Output from
.B pmie
is directed to standard output and standard error as follows:
.TP 5
.B stdout
Expression values printed in the verbose
.B \-v
mode and the output of
.B print
actions.
.TP
.B stderr
Error and warning messages for any syntactic or semantic problems during
expression parsing, and any semantic or performance metrics availability
problems during expression evaluation.
.SH EXAMPLES
The following example expressions demonstrate some of the capabilities
of the inference engine.
.P
The directory
.I $PCP_DEMOS_DIR/pmie
contains a number of other annotated examples of
.B pmie
expressions.
.P
The variable
.ft CW
delta
.ft 1
controls expression evaluation frequency.  Specify that subsequent expressions
be evaluated once a second, until further notice:
.P
.ft CW
.nf
.in +0.5i
delta = 1 sec;
.in
.fi
.ft 1
.P
If the total context switch rate exceeds 10000 per second per CPU,
then display an alarm notifier:
.P
.ft CW
.nf
.in +0.5i
kernel.all.pswitch / hinv.ncpu > 10000 count/sec
-> alarm "high context switch rate %v";
.in
.fi
.ft 1
.P
If the high context switch rate is sustained for 10 consecutive samples,
then launch
.BR top (1)
in an
.BR xwsh (1G)
window to monitor processes, but do this at most once every 5 minutes:
.P
.ft CW
.nf
.in +0.5i
all_sample (
    kernel.all.pswitch @0..9 > 10 Kcount/sec * hinv.ncpu
) -> shell 5 min "xwsh \-e 'top'";
.in
.fi
.ft 1
.P
The following rules are evaluated once every 20 seconds:
.P
.ft CW
.nf
.in +0.5i
delta = 20 sec;
.in
.fi
.ft 1
.P
If any disk is performing
more than 60 I/Os per second, then print a message identifying
the busy disk to standard output and
launch
.BR dkvis (1):
.P
.ft CW
.nf
.in +0.5i
some_inst (
    disk.dev.total > 60 count/sec
) -> print "busy disks:" " %i" &
     shell 5 min "dkvis";
.in
.fi
.ft 1
.P
Refine the preceding rule to apply only between the hours of 9am and 5pm,
and to require 3 of 4 consecutive samples to exceed the threshold before
executing the action:
.P
.ft CW
.nf
.in +0.5i
$hour >= 9 && $hour <= 17 &&
some_inst (
  75 %_sample (
    disk.dev.total @0..3 > 60 count/sec
  )
) -> print "disks busy for 20 sec:" " [%h]%i";
.in
.fi
.ft 1
.P
The following two rules are evaluated once every 10 minutes:
.P
.ft CW
.nf
.in +0.5i
delta = 10 min;
.in
.fi
.ft 1
.P
If either the / or the /usr filesystem is more than 95% full,
display an alarm popup, but not if it has already been displayed
during the last 4 hours:
.P
.ft CW
.nf
.in +0.5i
filesys.free #'/dev/root' /
    filesys.capacity #'/dev/root' < 0.05
-> alarm 4 hour "root filesystem (almost) full";

filesys.free #'/dev/usr' /
    filesys.capacity #'/dev/usr' < 0.05
-> alarm 4 hour "/usr filesystem (almost) full";
.in
.fi
.ft 1
.P
The following rule requires a machine that supports the PCP environment metrics.
If the machine environment temperature rises more than 2 degrees over a
10 minute interval, write an entry in the system log:
.P
.ft CW
.nf
.in +0.5i
environ.temp @0 - environ.temp @1 > 2
-> alarm "temperature rising fast" &
   syslog "machine room temperature rise alarm";
.in
.fi
.ft 1
.P
And something interesting if you have performance problems
with your Oracle database:
.P
.ft CW
.nf
.in +0.5i
// back to 30sec evaluations
delta = 30 sec;
db = "oracle.ptg1";
host = ":moomba.melbourne.sgi.com";
lru = "#'cache buffers lru chain'";
gets = "$db.latch.gets $host $lru";
total = "$db.latch.gets $host $lru +
         $db.latch.misses $host $lru +
         $db.latch.immisses $host $lru";

$total > 100 && $gets / $total < 0.2
-> alarm "high lru latch contention";
.in
.fi
.ft 1
.P
The following \f(CBruleset\fR will emit exactly one message
depending on the availability and value of the 1-minute load
average.
.P
.ft CW
.nf
.in +0.5i
delta = 1 minute;
ruleset
     kernel.all.load #'1 minute' > 10 * hinv.ncpu ->
         print "extreme load average %v"
else kernel.all.load #'1 minute' > 2 * hinv.ncpu ->
         print "moderate load average %v"
unknown ->
         print "load average unavailable"
otherwise ->
         print "load average OK"
;
.in
.fi
.ft 1
.SH QUICK START
The
.B pmie
specification language is powerful and large.
.P
To expedite rapid development of
.B pmie
rules, the
.BR pmieconf (1)
tool provides a facility for generating a
.B pmie
configuration file from a set of generalized
.B pmie
rules. 
The supplied set of rules covers
a wide range of performance scenarios.
.P
The
.I "Performance Co-Pilot User's and Administrator's Guide"
provides a detailed tutorial-style chapter covering
.BR pmie .
.SH EXPRESSION SYNTAX
This description is terse and informal.
For a more comprehensive description see the
.IR "Performance Co-Pilot User's and Administrator's Guide" .  
.P
A
.B pmie
specification is a sequence of semicolon terminated expressions.
.P
Basic operators are modeled on the arithmetic, relational and Boolean
operators of the C programming language.
Precedence rules are as expected, although the use of parentheses
is encouraged to enhance readability and remove ambiguity.
.P
Operands are performance metric names
(see
.BR pmns (5))
and the normal literal constants.
.P
Operands involving performance metrics may produce sets of values, as a
result of enumeration in the dimensions of
.BR hosts ,
.B instances
and
.BR time .
Special qualifiers may appear after a performance metric name to
define the enumeration in each dimension.  For example,
.P
.in +4n
.ft CW
kernel.percpu.cpu.user :foo :bar #cpu0 @0..2
.ft R
.in
.P
defines 6 values corresponding to the time spent executing in
user mode on CPU 0 on the hosts ``foo'' and ``bar'' over the last
3 consecutive samples.
The default interpretation in the absence of
.B :
(host),
.B #
(instance) and
.B @
(time) qualifiers is all instances at the most recent sample time
for the default source of PCP performance metrics.
.P
Host and instance names that do not follow the rules for variables
in programming languages, ie. alphabetic optionally followed by 
alphanumerics, should be enclosed in single quotes.
.P
Expression evaluation follows the law of ``least surprises''.
Where performance metrics have the semantics of a counter,
.B pmie
will automatically convert to a rate based upon consecutive samples
and the time interval between these samples.
All expressions are evaluated in double precision, and where
appropriate, automatically
scaled into canonical units of ``bytes'', ``seconds'' and ``counts''.
.P
A
.B rule
is a special form of expression that specifies a condition or logical
expression, a special operator (\c
.BR \-> )
and actions to be performed when the condition is found to be true.
.P
The following table summarizes the basic
.B pmie
operators:
.P
.ne 12v
.TS
box,center;
c | c
lf(CW) | l.
Operators	Explanation
_
+ \- * /	Arithmetic
< <= == >= > !=	Relational (value comparison)
! && ||	Boolean
->	Rule
\f(CBrising\fR	Boolean, false to true transition
\f(CBfalling\fR	Boolean, true to false transition
\f(CBrate\fR	Explicit rate conversion (rarely required)
.TE
.P
Aggregate operators may be used to aggregate or summarize along
one dimension of a set-valued expression.
The following aggregate operators map from a logical expression to
a logical expression of lower dimension.
.P
.ne 16v
.TS
box,center;
cw(2.4i) | c | cw(2.4i)
lf(CB) | l | l.
Operators	Type	Explanation
_
T{
.ad l
some_inst
.br
some_host
.br
some_sample
T}	Existential	T{
.ad l
True if at least one set member is true in the associated dimension
T}
_
T{
.ad l
all_inst
.br
all_host
.br
all_sample
T}	Universal	T{
.ad l
True if all set members are true in the associated dimension
T}
_
T{
.ad l
\f(CON\f(CB%_inst
.br
\f(CON\f(CB%_host
.br
\f(CON\f(CB%_sample\fR
T}	Percentile	T{
.ad l
True if at least \fIN\fP percent of set members are true in the associated dimension
T}
.TE
.P
The following instantial operators may be used to filter or limit a
set-valued logical expression, based on regular expression matching
of instance names.  The logical expression must be a set involving
the dimension of instances, and the regular expression is of the
form used by
.BR egrep (1)
or the Extended Regular Expressions of
.BR regcomp (3G).
.P
.ne 12v
.TS
box,center;
c | cw(4i)
lf(CB) | l.
Operators	Explanation
_
match_inst	T{
.ad l
For each value of the logical expression that is ``true'', the
result is ``true'' if the associated instance name matches the
regular expression.  Otherwise the result is ``false''.
T}
_
nomatch_inst	T{
.ad l
For each value of the logical expression that is ``true'', the
result is ``true'' if the associated instance name does
\fBnot\fP match the
regular expression.  Otherwise the result is ``false''.
T}
.TE
.P
For example, the expression below will be ``true'' for disks
attached to controllers 2 or 3 performing more than 20 operations per second:
.ft CW
.nf
.in +0.5i
match_inst "^dks[23]d" disk.dev.total > 20;
.in
.fi
.ft 1
.P
The following aggregate operators map from an arithmetic expression to
an arithmetic expression of lower dimension.
.P
.ne 20v
.TS
box,center;
cw(2.4i) | c | cw(2.4i)
lf(CB) | l | l.
Operators	Type	Explanation
_
T{
.ad l
min_inst
.br
min_host
.br
min_sample
T}	Extrema	T{
.ad l
Minimum value across all set members in the associated dimension
T}
_
T{
.ad l
max_inst
.br
max_host
.br
max_sample
T}	Extrema	T{
.ad l
Maximum value across all set members in the associated dimension
T}
_
T{
.ad l
sum_inst
.br
sum_host
.br
sum_sample
T}	Aggregate	T{
.ad l
Sum of values across all set members in the associated dimension
T}
_
T{
.ad l
avg_inst
.br
avg_host
.br
avg_sample
T}	Aggregate	T{
.ad l
Average value across all set members in the associated dimension
T}
.TE
.P
The aggregate operators \f(CWcount_inst\fR, \f(CWcount_host\fR and
\f(CWcount_sample\fR map from a logical expression to an arithmetic
expression of lower dimension by counting the number of set members
for which the expression is true in the associated dimension.
.P
For action rules, the following actions are defined:
.TS
box,center;
c | c
lf(CB) | l.
Operators	Explanation
_
alarm	Raise a visible alarm with \fBxconfirm\f1(1)
print	Display on standard output
shell	Execute with \fBsh\fR(1)
stomp	Send a STOMP message to a JMS server
syslog	Append a message to system log file
.TE
.P
Multiple actions may be separated by the \f(CW&\fR and \f(CW|\fR
operators to specify respectively sequential execution (both
actions are executed) and alternate execution (the second action
will only be executed if the execution of the first action returns
a non-zero error status.
.P
Arguments to actions are an optional suppression time, and then
one or more expressions (a string is an expression in this context).
Strings appearing as arguments to an action may include the following
special selectors that will be replaced at the time the action
is executed.
.TP 4n
\f(CB%h\fR
Host(s) that make the left-most top-level expression in the
condition true.
.TP
\f(CB%i\fR
Instance(s) that make the left-most top-level expression in the
condition true.
.TP
\f(CB%v\fR
One value from the left-most top-level expression in the
condition for each host and instance pair that
makes the condition true.
.P
Note that expansion of the special selectors is done by repeating the
whole argument once for each unique binding to any of the
qualifying special selectors.
For example if a rule were true for the host
.B mumble
with instances
.B grunt
and
.BR snort ,
and for host
.B fumble
the instance
.B puff
makes the rule true, then the action
.ft CW
.nf
.in +0.5i
\&...
-> shell myscript "Warning: %h:%i busy ";
.in
.fi
.ft 1
will execute
.B myscript
with the argument string "Warning: mumble:grunt busy Warning: mumble:snort busy Warning: fumble:puff busy".
.P
By comparison, if the action
.ft CW
.nf
.in +0.5i
\&...
-> shell myscript "Warning! busy:" " %h:%i";
.in
.fi
.ft 1
were executed under the same circumstances, then
.B myscript
would be executed with the argument string "Warning! busy: mumble:grunt mumble:snort fumble:puff".
.P
The semantics of the expansion of the special selectors leads to a
common usage pattern in an action, where one argument is a constant (contains no
special selectors) the second argument contains the desired
special selectors with minimal separator characters, and
an optional third argument provides a constant postscript (e.g. to terminate
any argument quoting from the first argument).
If necessary
post-processing (eg. in
.BR myscript )
can provide the necessary enumeration over each unique expansion
of the string containing just the special selectors.
.P
For complex conditions, the bindings to these selectors
is not obvious.
It is strongly recommended that
.B pmie
be used in
the debugging mode (specify the
.B \-W
command line option in particular) during rule development.
.SH BOOLEAN EXPRESSIONS
.B pmie
expressions that have the semantics of a Boolean, e.g.
\f(CWfoo.bar > 10\fR
or
\f(CBsome_inst\f(CW ( my.table < 0 )
.ft R
are assigned the values \f(CBtrue\fR or \f(CBfalse\fR or \f(CBunknown\fR.
A value is \f(CBunknown\fR if one or more of the underlying metric values
is unavailable, e.g.
.BR pmcd (1)
on the host cannot be contacted, the metric is not in the PCP archive,
no values are currently available, insufficient values have been fetched
to allow a rate converted value to be computed or insufficient values have
been fetched to instantiate the required number of samples in the
temporal domain.
.PP
Boolean operators follow the normal rules of Kleene logic (aka 3-valued
logic) when combining values that include \f(CBunknown\fR:
.TS
box,center;
c s|c s s
^ s|c s s
^ s|c|c|c
c|c|c|c|c
^|c|c|c|c.
A \f(CBand\fR B	B
	_
	\f(CBtrue\fR	\f(CBfalse\fR	\f(CBunknown\fR
_
A	\f(CBtrue\fR	\f(CBtrue\fR	\f(CBfalse\fR	\f(CBunknown\fR
	_	_	_	_
	\f(CBfalse\fR	\f(CBfalse\fR	\f(CBfalse\fR	\f(CBfalse\fR
	_	_	_	_
	\f(CBunknown\fR	\f(CBunknown\fR	\f(CBfalse\fR	\f(CBunknown\fR
.TE
.TS
box,center;
c s|c s s
^ s|c s s
^ s|c|c|c
c|c|c|c|c
^|c|c|c|c.
A \f(CBor\fR B	B
	_
B	\f(CBtrue\fR	\f(CBfalse\fR	\f(CBunknown\fR
_
A	\f(CBtrue\fR	\f(CBtrue\fR	\f(CBtrue\fR	\f(CBtrue\fR
	_	_	_	_
	\f(CBfalse\fR	\f(CBtrue\fR	\f(CBfalse\fR	\f(CBunknown\fR
	_	_	_	_
	\f(CBunknown\fR	\f(CBtrue\fR	\f(CBunknown\fR	\f(CBunknown\fR
.TE
.TS
box,center;
c|c.
A	\f(CBnot\fR A
_
\f(CBtrue\fR	\f(CBfalse\fR
_
\f(CBfalse\fR	\f(CBtrue\fR
_
\f(CBunknown\fR	\f(CBunknown\fR
.TE
.SH RULESETS
The \f(CBruleset\fR clause is used to define a set of rules and
actions that are evaluated in order until some action is executed,
at which point the remaining rules and actions are skipped until
the \f(CBruleset\fR is again scheduled for evaluation.
The keyword \f(CBelse\fR is used to separate rules.
After one or more regular rules (with a predicate and an action), a
\f(CBruleset\fR may include an optional
.br
.ti +0.5i
\f(CBunknown\fR -> action
.br
clause, optionally followed by a
.br
.ti +0.5i
\f(CBotherwise\fR -> action
.br
clause.
.PP
If all of the predicates in the rules evaluate to \f(CBunknown\fR and
an \f(CBunknown\fR clause has been specified then action associated
with the \f(CBunknown\fR clause will be executed.
.PP
If no rule predicate is \f(CBtrue\fR and the \f(CBunknown\fR action
is either not specified or not
executed and an \f(CBotherwise\fR clause has been specified,
then the action associated with the \f(CBotherwise\fR clause will be executed.
.SH SCALE FACTORS
Scale factors may be appended to arithmetic expressions and force
linear scaling of the value to canonical units.  Simple scale factors
are constructed from the keywords:
\f(CBnanosecond\fR, \f(CBnanosec\fR, \f(CBnsec\f1,
\f(CBmicrosecond\fR, \f(CBmicrosec\fR, \f(CBusec\f1,
\f(CBmillisecond\fR, \f(CBmillisec\fR, \f(CBmsec\f1,
\f(CBsecond\fR, \f(CBsec\fR, \f(CBminute\fR, \f(CBmin\fR, \f(CBhour\f1,
\f(CBbyte\fR, \f(CBKbyte\fR, \f(CBMbyte\fR, \f(CBGbyte\fR, \f(CBTbyte\f1,
\f(CBcount\fR, \f(CBKcount\fR and \f(CBMcount\fR,
and the operator \f(CW/\fR, for example ``\f(CBKbytes / hour\f1''.
.SH MACROS
Macros are defined using expressions of the form:
.P
.in +0.5i
\fIname\fR = \fIconstexpr\f1;
.in
.P
Where
.I name
follows the normal rules
for variables
in programming languages, ie. alphabetic optionally followed by 
alphanumerics.
.I constexpr
must be a constant expression, either a string
(enclosed in double quotes) or an arithmetic expression optionally
followed by a scale factor.
.P
Macros are expanded when their name, prefixed by a dollar (\f(CW$\fR)
appears in an expression, and macros may be nested within a
.I constexpr
string.
.P
The following reserved macro names are understood.
.TP 10n
\f(CBminute\f1
Current minute of the hour.
.TP
\f(CBhour\f1
Current hour of the day, in the range 0 to 23.
.TP
\f(CBday\f1
Current day of the month, in the range 1 to 31.
.TP
\f(CBmonth\f1
Current month of the year, in the range 0 (January) to 11 (December).
.TP
\f(CByear\f1
Current year.
.TP
\f(CBday_of_week\f1
Current day of the week, in the range 0 (Sunday) to 6 (Saturday).
.TP
\f(CBdelta\f1
Sample interval in effect for this expression.
.P
Dates and times are presented in the
reporting time zone (see description of
.B \-Z
and
.B \-z
command line options above).
.SH AUTOMATIC RESTART
It is often useful for
.B pmie
processes to be started and stopped when the local host is booted
or shutdown, or when they have been detected as no longer running
(when they have unexpectedly exited for some reason).
Refer to 
.BR pmie_check (1)
for details on automating this process.
.SH EVENT MONITORING
It is common for production systems to be monitored in a central
location.
Traditionally on UNIX systems this has been performed by the system
log facilities \- see
.BR logger (1),
and
.BR syslogd (1).
On Windows, communication with the system event log is handled by 
.BR pcp-eventlog (1).
.P
.B pmie
fits into this model when rules use the
.I syslog
action.
Note that if the action string begins with \-p (priority) and/or \-t (tag)
then these are extracted from the string and treated in the same way as in
.BR logger (1)
and
.BR pcp-eventlog (1).
.P
However, it is common to have other event monitoring frameworks also,
into which you may wish to incorporate performance events from
.BR pmie .
You can often use the
.I shell
action to send events to these frameworks, as they usually provide
their a program for injecting events into the framework from external
sources.
.P
A final option is use of the
.I stomp
(Streaming Text Oriented Messaging Protocol) action, which allows
.B pmie
to connect to a central JMS (Java Messaging System) server and send
events to the PMIE topic.
Tools can be written to extract these text messages and present them
to operations people (via desktop popup windows, etc).
Use of the
.I stomp
action requires a stomp configuration file to be setup, which specifies
the location of the JMS server host, port number, and username/password.
.P
The format of this file is as follows:
.P
.ft CW
.nf
.in +0.5i
host=messages.sgi.com   # this is the JMS server (required)
port=61616              # and its listening here (required)
timeout=2               # seconds to wait for server (optional)
username=joe            # (required)
password=j03ST0MP       # (required)
topic=PMIE              # JMS topic for pmie messages (optional)
.in
.fi
.ft 1
.P
The timeout value specifies the time (in seconds) that
.B pmie
should wait for acknowledgements from the JMS server after
sending a message (as required by the STOMP protocol).
Note that on startup,
.B pmie
will wait indefinitely for a connection, and will not
begin rule evaluation until that initial connection has
been established.
Should the connection to the JMS server be lost at any
time while
.B pmie
is running,
.B pmie
will attempt to reconnect on each subsequent truthful
evaluation of a rule with a
.I stomp
action, but not more than once per minute.
This is to avoid contributing to network congestion.
In this situation, where the STOMP connection to the JMS server
has been severed, the
.I stomp
action will return a non-zero error value.
.SH FILES
.PD 0
.TP 10
.BI $PCP_DEMOS_DIR/pmie/ *
annotated example rules
.TP
.BI $PCP_VAR_DIR/pmns/ *
default PMNS specification files
.TP
.BI $PCP_TMP_DIR/pmie
.B pmie
maintains files in this directory to identify the running
.B pmie
instances and to export runtime information about each instance \- this data
forms the basis of the pmcd.pmie performance metrics
.TP
.BI $PCP_PMIECONTROL_PATH
the default set of
.B pmie
instances to start at boot time \- refer to
.BR pmie_check (1)
for details
.TP
.BI $PCP_SYSCONF_DIR/pmie/ *
the predefined alarm action scripts (\c
.BR email ,
.BR log ,
.B popup
and
.BR syslog ),
the example action script (\c
.BR sample ) and
the concurrent action control file (\c
.BR control.master ).
.PD
.SH BUGS
The lexical scanner and parser will attempt to recover after an
error in the input expressions.
Parsing resumes after skipping input up to
the next semi-colon (;), however during this skipping
process the scanner is ignorant of comments and strings, so an
embedded semi-colon may cause parsing to resume at an unexpected
place.  This behavior is largely benign, as until the initial
syntax error is corrected,
.B pmie 
will not attempt any expression evaluation.
.SH "PCP ENVIRONMENT"
Environment variables with the prefix
.B PCP_
are used to parameterize the file and directory names
used by PCP.
On each installation, the file
.I /etc/pcp.conf
contains the local values for these variables.
The
.B $PCP_CONF
variable may be used to specify an alternative
configuration file,
as described in
.BR pcp.conf (5).
.SH UNIX SEE ALSO
.BR logger (1).
.SH WINDOWS SEE ALSO
.BR pcp-eventlog (1).
.SH SEE ALSO
.BR PCPIntro (1),
.BR pmcd (1),
.BR pmdumplog (1),
.BR pmieconf (1),
.BR pmie_check (1),
.BR pminfo (1),
.BR pmlogger (1),
.BR pmval (1),
.BR PMAPI (3),
.BR pcp.conf (5)
and
.BR pcp.env (5).
.SH USER GUIDE
For a more complete description of the
.B pmie
language, refer to the
.BR "Performance Co-Pilot Users and Administrators Guide" .
This is available online from:
.in +4n
.nf
http://www.performancecopilot.org/doc/pcp-users-and-administrators-guide.pdf
.fi
.in -4n