Linux: How to put a load on system memory?

Question

I\'m working on a small function, that gives my users a picture of how occupied the CPU is.

I\'m using cat /proc/loadavg, which returns the well known 3 num

Answer 1

Use "memtester" to do your memory regression tests in Linux.

Answer 2

I took this program and modify the line: mem = 1024*1024*512; //512 mb to say this: mem = 1*1024*1024*1024; //1 GB and compile it.

$ gcc iss_mem.c -o iss_mem

And write a bash wrapper around the compiled version of the C program above. It helps me generate a lot of memory load in my server.

#!/bin/bash
# Author: Mamadou Lamine Diatta
#         Senior Principal Consultant / Infrastructure Architect
# Email:  diatta at post dot harvard dot edu
# --------------------------------------------------------------------------------------
# *************************************************************************************

memsize_kb=`grep -i MemTotal /proc/meminfo | awk '{print $2}'`
MemTotal=$(($memsize_kb*1024))
for i in `seq 1 50`
do

        echo "`date +"%F:%H:%M:%S"` ----------------- Running [ $i ] iteration(s)"
        MemToAlloc=$((1*1024*1204*1204))
            # 1Gb of memory per iss_mem call
        TRESHOLD=$(($MemTotal/$MemToAlloc))
             # We are not supposed to make the system
             # run out of memory
        rand=1000
            # High enough to force a new one
        while (( $rand > $TRESHOLD ))
        do
                rand=$(($RANDOM/1000))
        done
        if [ $rand -eq 0 ]
        then
                rand=1
        fi

        echo `date +"%F:%H:%M:%S"` Running $rand iss_mem in parallel ...
        for j in `seq 1 $rand`
        do
             ${ISSHOME}/bin/iss_mem > /dev/null &
                # NOTE: gcc iss_mem.c -o iss_mem
        done

        sleep 180
        jobs -p
        kill `jobs -p`

        sleep 30


done
# -------------------------------------------------------------------------------------
# *************************************************************************************

Answer 3

you can stress utility, as it is a workload generator tool designed to subject your system to a configurable measure of CPU, memory, I/O and disk stress.

To run 1 vm stressor using 1GB of virtual memory for 60s, enter:

stress --vm 1 --vm-bytes 1G --vm-keep -t 60s

Answer 4

1G memory

python -c 'a="a"*1024**3;raw_input()'

Answer 5

mark@localhost$ time pi 1048576 | egrep '.*total$'

Is a simple benchmarking command that will give your cpu a rousting, post your times :D

Answer 6

while true;
    do openssl speed;
done

also the stress program will let you load the cpu/mem/disk to the levels you want to simulate:

• http://weather.ou.edu/~apw/projects/stress/

stress is a deliberately simple workload generator for POSIX systems. It imposes a configurable amount of CPU, memory, I/O, and disk stress on the system. It is written in C, and is free software licensed under the GPLv2.

to maintain a particular level of cpu utilization, say 30%, try cpulimit:

• http://cpulimit.sourceforge.net/

it will adapt to the current system environment and adjust for any other activity on the system.

there's also a patch to the kernel for native cpu rate limits here: http://lwn.net/Articles/185489/