3

I don't won't to use swap file (due to some bug in kernel or AMD driver).

I wan't to have some util running and monitoring free system memory and alerting me when it becomes less than some specified limit.

This will notify me that I need to close some applications (or browser tabs) to avoid system freeze due to some strange kswapd0 I/O activity (probably another bug).

Is there any appropriate software?

UPDATE:

I've redesigned script provided by Gary for my need and want to share it

#!/bin/bash

#Minimum available memory limit, MB
THRESHOLD=400


#Check time interval, sec
INTERVAL=30


while :
do


free=$(free -m | awk '/^Mem:/{print $4}')
buffers=$(free -m | awk '/^Mem:/{print $6}')
cached=$(free -m | awk '/^Mem:/{print $7}')
available=$(free -m | awk '/^-\/+/{print $4}')

message="Free $free""MB"", buffers $buffers""MB"", cached $cached""MB"", available $available""MB"""

if [ $available -lt $THRESHOLD ]
    then
    notify-send "Memory is running out!" "$message"
fi

echo $message

sleep $INTERVAL




done
Carter
  • 322

2 Answers2

6

You could try using free.

free -s n will update the output every n seconds. Wrap that in an if for whatever threshold you feel is "too much memory" being used, and display a message when it reaches that point.

EDIT: Here's the script I came up with. Rough, but it works.

#Checks for low memory.

#!/bin/bash

#cutoff_frac is basically how much used memory can be at in terms of how much
#total memory you have...2 is 1/2 of 100% or an alert when you're using 50% mem, etc.
cutoff_frac=2

total_mem=$(free|awk '/^Mem:/{print $2}')
let "threshold = $total_mem / $cutoff_frac"

while :
do

    free_mem=$(free|awk '/^Mem:/{print $4}')

    if [ $free_mem -lt $threshold ]
        then
        notify-send "Low memory!!"
    fi

    sleep 5

done

exit
Gary
  • 4,042
1

PHP version of the script:

The Free memory as shown in the system moniter is : Free= Total-(Used-buffered-cached)

What is the difference between the memory usage report in System Monitor and the one by free?

NOTE: To run this script as a cron job use: 

* * * * *  env DISPLAY=:0.0 path/to/file 90

or 

@restart  env DISPLAY=:0.0 path/to/file

uncomment the while loop to run it manually:

Code: 

#!/usr/bin/php
<?php
$alert_percent=($argc>1)?(int)$argv[1]:90;
//$interval=($argc>2):(int)$argv[2]:25;



//while(true)
//{
 exec("free",$free);

$free=implode(' ',$free);
preg_match_all("/(?<=\s)\d+/",$free,$match);

list($total_mem,$used_mem,$free_mem,$shared_mem,$buffered_mem,$cached_mem)=$match[0];

$used_mem-=($buffered_mem+$cached_mem);

$percent_used=(int)(($used_mem*100)/$total_mem);

if($percent_used>$alert_percent)
exec("notify-send 'Low Memory: $percent_used% used'");

//sleep($interval);
//}
exit();
?>
Community
  • 1
StandardSpecification
  • 281