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PMIE

Section: User Commands (1)
Updated: SGI
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NAME

pmie - inference engine for performance metrics  

SYNOPSIS

pmie [-bCdefHVvWxz] [-A align] [-a archive] [-c filename] [-h host] [-l logfile] [-j stompfile] [-n pmnsfile] [-O offset] [-S starttime] [-T endtime] [-t interval] [-Z timezone] [filename ...]  

DESCRIPTION

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.

As well as computing arithmetic and logical values, 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.

The expressions to be evaluated are read from configuration files specified by one or more filename arguments. In the absence of any filename, expressions are read from standard input.

A description of the command line options specific to pmie follows:

-a
archive is the base name of a PCP archive log written by pmlogger(1). Multiple instances of the -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 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.
-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 -l option. The -b option is always used for pmie instances launched from pmie_check(1).
-C
Parse the configuration file(s) and exit before performing any evaluations. Any errors in the configuration file are reported.
-c
An alternative to specifying filename at the end of the command line.
-d
Normally pmie would be launched as a non-interactive process to monitor and manage the performance of one or more hosts. Given the -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.
-e
When used with -V, -v or -W, this option forces timestamps to be reported with each expression. The timestamps are in ctime(3) format, enclosed in parenthesis and appear after the expression name and before the expression value, e.g.
        expr_1 (Tue Feb  6 19:55:10 2001): 12
-f
If the -l option is specified and there is no -a option (ie. real-time monitoring) then pmie is run as a daemon in the background (in all other cases foreground is the default). The -f option forces pmie to be run in the foreground, independent of any other options.
-H
The default hostname written to the stats file will not be looked up via 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.
-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 host argument overrides this default. It does not override hosts explicitly named in the expressions being evaluated.
-l
Standard error is sent to logfile.
-j
An alternative STOMP protocol configuration is loaded from stompfile. If this option is not used, and the stomp action is used in any rule, the default location $PCP_VAR_DIR/pmie/config/stomp will be used.
-n
An alternative Performance Metrics Name Space (PMNS) is loaded from the file pmnsfile.
-t
The interval argument follows the syntax described in 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 pmie variable delta described below. The default is 10.0 seconds.
-v
Unless one of the verbose options -V, -v or -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 -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 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.
-V
This option has the same effect as the -v option, except that the name of the host and instance (if applicable) are printed as well as expression values.
-W
This option has the same effect as the -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.
-x
Execute in domain agent mode. This mode is used within the Performance Co-Pilot product to derive values for summary metrics, see pmdasummary(1). Only restricted functionality is available in this mode (expressions with actions may not be used).
-Z
Change the reporting timezone to timezone in the format of the environment variable TZ as described in environ(5).
-z
Change the reporting timezone to the timezone of the host that is the source of the performance metrics, as identified via either the -h option or the first named archive (as described above for the -a option).

The -S, -T, -O, and -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 PCPIntro(1) for a complete description of these options.

Output from pmie is directed to standard output and standard error as follows:

stdout
Expression values printed in the verbose -v mode and the output of print actions.
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.
 

EXAMPLES

The following example expressions demonstrate some of the capabilities of the inference engine.

The directory $PCP_DEMOS_DIR/pmie contains a number of other annotated examples of pmie expressions.

The variable delta controls expression evaluation frequency. Specify that subsequent expressions be evaluated once a second, until further notice:

delta = 1 sec;

If total syscall rate exceeds 5000 per second per CPU, then display an alarm notifier:

kernel.all.syscall / hinv.ncpu > 5000 count/sec
-> alarm "high syscall rate";

If the high syscall rate is sustained for 10 consecutive samples, then launch top(1) in an xwsh(1G) window to monitor processes, but do this at most once every 5 minutes:

all_sample (
    kernel.all.syscall @0..9 > 5000 count/sec * hinv.ncpu
) -> shell 5 min "xwsh -e 'top'";

The following rules are evaluated once every 20 seconds:

delta = 20 sec;

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 dkvis(1):

some_inst (
    disk.dev.total > 60 count/sec
) -> print "disk %i busy " &
     shell 5 min "dkvis";

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:

$hour >= 9 && $hour <= 17 &&
some_inst (
  75 %_sample (
    disk.dev.total @0..3 > 60 count/sec
  )
) -> print "disk %i busy ";

The following rules are evaluated once every 10 minutes:

delta = 10 min;

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:

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";

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:

environ.temp @0 - environ.temp @1 > 2
-> alarm "temperature rising fast" &
   syslog "machine room temperature rise alarm";

And last, something interesting if you have performance problems with your Oracle database:

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";
 

QUICK START

The pmie specification language is powerful and large.

To expedite rapid development of pmie rules, the pmieconf(1) tool provides a facility for generating a pmie configuration file from a set of generalized pmie rules. The supplied set of rules covers a wide range of performance scenarios.

The pmrules(1) tool provides a GUI-based facility for generating pmie rules from parametrized templates. The supplied templates cover a wide range of performance scenarios.

The development efforts of the PCP engineering team are focused on pmieconf rather than pmrules, and thus pmieconf is the recommended tool for quickly deploying useful pmie rules.

The Performance Co-Pilot User's and Administrator's Guide provides a detailed tutorial-style chapter covering pmie.  

EXPRESSION SYNTAX

This description is terse and informal. For a more comprehensive description see the Performance Co-Pilot User's and Administrator's Guide.

A pmie specification is a sequence of semicolon terminated expressions.

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.

Operands are performance metric names (see pmns(4)) and the normal literal constants.

Operands involving performance metrics may produce sets of values, as a result of enumeration in the dimensions of hosts, instances and time. Special qualifiers may appear after a performance metric name to define the enumeration in each dimension. For example,

kernel.percpu.cpu.user :foo :bar #cpu0 @0..2

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 : (host), # (instance) and @ (time) qualifiers is all instances at the most recent sample time for the default source of PCP performance metrics.

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.

Expression evaluation follows the law of ``least surprises''. Where performance metrics have the semantics of a counter, 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''.

A rule is a special form of expression that specifies a condition or logical expression, a special operator (->) and actions to be performed when the condition is found to be true.

The following table summarizes the basic pmie operators:

OperatorsExplanation

+ - * /Arithmetic
< <= == >= > !=Relational (value comparison)
! && ||Boolean
->Rule
risingBoolean, false to true transition
fallingBoolean, true to false transition
rateExplicit rate conversion (rarely required)

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.

OperatorsTypeExplanation

some_inst
some_host
some_sample
Existential True if at least one set member is true in the associated dimension

all_inst
all_host
all_sample
Universal True if all set members are true in the associated dimension

N%_inst
N%_host
N%_sample
Percentile True if at least N percent of set members are true in the associated dimension

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 egrep(1) or the Extended Regular Expressions of regcomp(3G).

OperatorsExplanation

match_inst 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''.

nomatch_inst For each value of the logical expression that is ``true'', the result is ``true'' if the associated instance name does not match the regular expression. Otherwise the result is ``false''.

For example, the expression below will be ``true'' for disks attached to controllers 2 or 3 performing more than 20 operations per second:

match_inst "^dks[23]d" disk.dev.total > 20;

The following aggregate operators map from an arithmetic expression to an arithmetic expression of lower dimension.

OperatorsTypeExplanation

min_inst
min_host
min_sample
Extrema Minimum value across all set members in the associated dimension

max_inst
max_host
max_sample
Extrema Maximum value across all set members in the associated dimension

sum_inst
sum_host
sum_sample
Aggregate Sum of values across all set members in the associated dimension

avg_inst
avg_host
avg_sample
Aggregate Average value across all set members in the associated dimension

The aggregate operators count_inst, count_host and count_sample 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.

For action rules, the following actions are defined:

OperatorsExplanation

alarmRaise a visible alarm with xconfirm(1)
printDisplay on standard output
shellExecute with sh(1)
stompSend a STOMP message to a JMS server
syslogAppend a message to system log file

Multiple actions may be separated by the & and | 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.

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.

%h
Host(s) that make the left-most top-level expression in the condition true.
%i
Instance(s) that make the left-most top-level expression in the condition true.
%v
Values(s) from the left-most top-level expression in the condition subject to the host and instance assignments that make the condition true.

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 mumble with instances grunt and snort, and for host fumble the instance puff makes the rule true, then the action

...
-> shell myscript "Warning: %h-%i busy ";
will execute myscript with the argument string "Warning: mumble-grunt busy Warning: mumble-snort busy Warning: fumble-puff busy".

By comparison, if the action

...
-> shell myscript "'Warning! busy:" " %i@%h" "'";
were executed under the same circumstances, then myscript would be executed with the argument string '"Warning! busy: grunt@mumble snort@mumble puff@fumble"'.

The semantics of the expansion of the special selectors leads to a common usage, 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 myscript) can provide the necessary enumeration over each unique expansion of the string containing just the special selectors.

For complex conditions, the bindings to these selectors is not obvious. It is strongly recommended that pmie be used in the debugging mode (specify the -W command line option in particular) during rule development.  

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: nanosecond, nanosec, nsec, microsecond, microsec, usec, millisecond, millisec, msec, second, sec, minute, min, hour, byte, Kbyte, Mbyte, Gbyte, Tbyte, count, Kcount, Mcount, Gcount and Tcount, and the operator /, for example ``Kbytes / hour''.  

MACROS

Macros are defined using expressions of the form:

name = constexpr;

Where name follows the normal rules for variables in programming languages, ie. alphabetic optionally followed by alphanumerics. constexpr must be a constant expression, either a string (enclosed in double quotes) or an arithmetic expression optionally followed by a scale factor.

Macros are expanded when their name, prefixed by a dollar ($) appears in an expression, and macros may be nested within a constexpr string.

The following reserved macro names are understood.

minute
Current minute of the hour.
hour
Current hour of the day, in the range 0 to 23.
day
Current day of the month, in the range 1 to 31.
month
Current month of the year, in the range 0 (January) to 11 (December).
year
Current year.
day_of_week
Current day of the week, in the range 0 (Sunday) to 6 (Saturday).
delta
Sample interval in effect for this expression.

Dates and times are presented in the reporting time zone (see description of -Z and -z command line options above).  

AUTOMATIC RESTART

It is often useful for 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 pmie_check(1) for details on automating this process.  

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 logger(1), and syslogd(1). On Windows, communication with the system event log is handled by pcp-eventlog(1).

pmie fits into this model when rules use the 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 logger(1) and pcp-eventlog(1).

However, it is common to have other event monitoring frameworks also, into which you may wish to incorporate performance events from pmie. You can often use the shell action to send events to these frameworks, as they usually provide their a program for injecting events into the framework from external sources.

A final option is use of the stomp (Streaming Text Oriented Messaging Protocol) action, which allows 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 stomp action requires a stomp configuration file to be setup, which specifies the location of the JMS server host, port number, and username/password.

The format of this file is as follows:

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)

The timeout value specifies the time (in seconds) that pmie should wait for acknowledgements from the JMS server after sending a message (as required by the STOMP protocol). Note that on startup, pmie will wait indefinately 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 pmie is running, pmie will attempt to reconnect on each subsequent truthful evaluation of a rule with a 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 stomp action will return a non-zero error value.  

FILES

$PCP_DEMOS_DIR/pmie/*
annotated example rules
$PCP_VAR_DIR/pmns/*
default PMNS specification files
$PCP_TMP_DIR/pmie
pmie maintains files in this directory to identify the running pmie instances and to export runtime information about each instance - this data forms the basis of the pmcd.pmie performance metrics
$PCP_PMIECONTROL_PATH
the default set of pmie instances to start at boot time - refer to pmie_check(1) for details
$PCP_VAR_DIR/config/pmie/*
the predefined alarm action scripts (email, log, popup and syslog), the example action script (sample)and the concurrent action control file (control.master, see also pmrules(1)).
/usr/pcp/lib/pmie-common
common shell procedures for the predefined alarm action scripts
 

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, pmie will not attempt any expression evaluation.  

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(4).  

UNIX SEE ALSO

logger(1).  

WINDOWS SEE ALSO

pcp-eventlog(1).  

SEE ALSO

PCPIntro(1), pmcd(1), pmdumplog(1), pmieconf(1), pmie_check(1), pminfo(1), pmlogger(1), pmval(1), PMAPI(3), pcp.conf(4) and pcp.env(4).  

USER GUIDE

For a more complete description of the pmie language, refer to the Performance Co-Pilot Users and Administrators Guide. This is distributed in insight(1) format as part of the pcp.books subsystem, or in HTML format from:
http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi?\
    db=bks&fname=/SGI_Admin/books/PCP_IRIX/sgi_html/ch05.html


 

Index

NAME
SYNOPSIS
DESCRIPTION
EXAMPLES
QUICK START
EXPRESSION SYNTAX
SCALE FACTORS
MACROS
AUTOMATIC RESTART
EVENT MONITORING
FILES
BUGS
PCP ENVIRONMENT
UNIX SEE ALSO
WINDOWS SEE ALSO
SEE ALSO
USER GUIDE

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Time: 04:33:15 GMT, October 25, 2010