A3 SystemStatistics

Chapter A3
SystemStatistics

Author(s):

Ian Hinder

Date:

2010/04/06 11:00:00

A3.1 Abstract

Thorn SystemStatistics collects information about the system on which a Cactus process is running and stores it in Cactus variables. These variables can then be output and reduced using the standard Cactus methods such as IOBasic and IOScalar.

A3.2 Purpose

When running a Cactus simulation, there are often features of the system on which it is running which can affect the simulation. For example, Cactus processes take a certain amount of memory, and if this exceeds the memory available on the system, the Cactus process will either start to swap, significantly reducing performance, or will terminate. It can be useful to determine quantities such as memory usage of a Cactus process, and that is the purpose of this thorn. The thorn currently provides grid arrays which are filled with memory-related information.

A3.3 SystemStatistics Parameters

This thorn has no parameters.

A3.4 Examples

IOBasic::outInfo_every                  = 256
IOBasic::outInfo_reductions             = "minimum maximum"
IOBasic::outInfo_vars                   = "SystemStatistics::maxrss_mb"

IOScalar::outScalar_every               = 256
IOScalar::outScalar_reductions          = "minimum maximum average"
IOScalar::outScalar_vars                = "SystemStatistics::process_memory_mb"

The resulting screen output would look like this:

-----------------------------------------
Iteration      Time | *TISTICS::maxrss_mb
                    |   minimum   maximum
-----------------------------------------
        0     0.000 |        52        54
      256     0.005 |        53        55
      512     0.010 |        53        55
      768     0.015 |        53        55
     1024     0.020 |        53        55

and the reduced scalar output in systemstatistics::process_memory_mb.maximum.asc would look like this:

# SYSTEMSTATISTICS::maxrss_mb (systemstatistics::process_memory_mb)
# 1:iteration 2:time 3:data
# data columns: 3:maxrss_mb 4:majflt_mb 5:arena_mb 6:ordblks_mb 7:hblks_mb 8:hblkhd_mb 9:uordblks_mb 10:fordblks_mb 11:keepcost_mb
0 0 54 7 50 0 0 0 39 12 11
256 0.00498610682309355 55 7 51 0 0 0 39 12 11
512 0.0099722136461871 55 7 51 0 0 0 39 12 11
768 0.0149583204692806 55 7 51 0 0 0 39 12 11
1024 0.0199444272923742 55 7 51 0 0 0 39 12 11

A3.5 Comments

There has been some discussion concerning whether it would be better to use Cactus clocks to store this information.
The current implementation stores memory usage in CCTK_INT variables. Since memory sizes of many gigabytes are common, this could lead to overflow. It would probably be better to use CCTK_REAL variables instead.
The thorn currently has variables for bytes, kilobytes and megabytes for each quantity. It might be better to remove these and let the output mechanism format the variables in an easy to understand form.
This thorn uses information from the /proc filesystem where it is available. The Resident Set Size (RSS) is also read correctly on Mac OS, where /proc is not available.

A3.6 Parameters

A3.7 Interfaces

General

Implements:

systemstatistics

Grid Variables

PRIVATE GROUPS


Group Names	Variable Names	Details

process_memory		compact	0
	maxrss	description	Process memory statistics
	majflt	dimensions	1
	arena	distribution	CONSTANT
	ordblks	group type	ARRAY
	hblks	size	1
	hblkhd	stagger type	NONE
	uordblks	tags	Checkpoint=”no”
	fordblks	timelevels	1
	keepcost	variable type	INT

process_memory_mb		compact	0
	maxrss_mb	description	Run memory statistics in MB
	majflt_mb	dimensions	1
	arena_mb	distribution	CONSTANT
	ordblks_mb	group type	ARRAY
	hblks_mb	size	1
	hblkhd_mb	stagger type	NONE
	uordblks_mb	tags	Checkpoint=”no”
	fordblks_mb	timelevels	1
	keepcost_mb	variable type	INT

process_memory_kb		compact	0
	maxrss_kb	description	Run memory statistics in KB
	majflt_kb	dimensions	1
	arena_kb	distribution	CONSTANT
	ordblks_kb	group type	ARRAY
	hblks_kb	size	1
	hblkhd_kb	stagger type	NONE
	uordblks_kb	tags	Checkpoint=”no”
	fordblks_kb	timelevels	1
	keepcost_kb	variable type	INT

A3.8 Schedule

This section lists all the variables which are assigned storage by thorn AEIThorns/SystemStatistics. Storage can either last for the duration of the run (Always means that if this thorn is activated storage will be assigned, Conditional means that if this thorn is activated storage will be assigned for the duration of the run if some condition is met), or can be turned on for the duration of a schedule function.

Storage

Always:
process_memory
process_memory_mb
process_memory_kb

Scheduled Functions

CCTK_ANALYSIS

systemstatistics_collect

collect system statistics

	Language:	c
	Options:	global
	Type:	function

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Chapter A3SystemStatistics