I'm using stress-ng and not able to reach 100% cpu load. stress-ng, version 0.09.60 on kernel 4.1.35 a quad core ARM processor. I've used the following commands:
stress-ng --matrix 4 --tz --ignite-cpu
I noticed that the cpu climbs up in 25% increments to 75% when I use the following:
stress-ng --matrix 1 --tz --ignite-cpu → 25% cpu load
stress-ng --matrix 2 --tz --ignite-cpu → 50% cpu load
stress-ng --matrix 3 --tz --ignite-cpu → 75% cpu load
Any higher matrix number of workers does not increase the load, for example
stress-ng --matrix 10 --tz --ignite-cpu → 75% cpu load
I've also tried as referenced
stress-ng -c 4 -l 100 or stress-ng -c 0 -l 100 and it still doesn't go above 75%. In fact those --cpu-load options don't keep cpu up as consistently as --matrix option.
I wonder if you want to use dd to increase CPU benchmark. I usually use it to test CPU usage alarm.
dd if=/dev/zero of=/storage/test bs=1M count=1024 | md5sum
ref: How to use 'dd' to benchmark your disk or CPU?
Perhaps not many people use this, but 'dd' in conjunction with any stream-processing CPU-intensive program can also be used as a simple CPU benchmark! It may be not very accurate, but the huge advantage is that it doesn't require installing any additional software whatsoever, and typically you can run this “out of the box” on any GNU/Linux system.
Related
I want to test performance of one of my other program with different memory load like 10%, 20%, 30% etc. To generate memory load , I used stress tool.
When I execute
stress -m 1 --vm-bytes 128M
or
stress -m 1 --vm-bytes 256M
top command shows
% CPU %Memory
99 5 - 10%
Maximum 10% memory load was generating, not exceeding any more.
How to generate 20%, 30% memory load?
Is there any other tool available for generating memory load in linux
When I try to restrict CPU utilization using cpulimit, it doesn't change the CPU utilization.
cpulimit -p <pid> -l 20
Is it possible to restrict CPU utilization and memory load at the same time - like 10% CPU Utilization, 10% Memory, 10 % CPU Utilization, 50% Memory load ?
I am using Intel(R) Core(TM) i7-3770 CPU # 3.40GHz, Ubuntu 12.04.5 LTS , 2GB RAM, 8 CPU core.
I'm really confused. Why does the load average and %CPU does not match the process CPU usage below. It seems like the process is eating up a lot of CPU while the AWS EC2 meters only says 25% CPU is used.
%CPU -- CPU Usage : The percentage of your CPU that is being used by the process. By default, top displays this as a percentage
of a single CPU. On multi-core systems, you can have percentages
that are greater than 100%. For example, if 3 cores are at 60% use,
top will show a CPU use of 180%.
You can toggle this behavior by hitting Shift+i while top is running to show the overall percentage of available
CPUs in use.
load average: 22.56, 24.99, 26.51
From left to right, these numbers show you the average load over the last 1 minute, the last 5 minutes, and the last 15 minutes.
us -- User CPU time
The time the CPU has spent running users' processes that are not niced.
sy -- System CPU time
The time the CPU has spent running the kernel and its processes.
ni -- Nice CPU time
The time the CPU has spent running users' proccess that have been niced.
wa -- iowait
Amount of time the CPU has been waiting for I/O to complete.
hi -- Hardware IRQ
The amount of time the CPU has been servicing hardware interrupts.
si -- Software Interrupts
The amount of time the CPU has been servicing software interrupts.
st -- Steal Time
The amount of CPU 'stolen' from this virtual machine by the hypervisor for other tasks (such as running another virtual machine).
See more details from In Linux “top” command what are us, sy, ni, id, wa, hi, si and st (for CPU usage).
after you run command "top" you can press "1" on your keyboard to see individual CPU utilization, more details when you run command "man top"
Note process "msqld" can use CPU from several resources and its utilization % could easily go beyond 100% in "top" display.
Hi maybe your app using single core and other cores are free. I think your instance has 4 CPU core and one is utilizing 100%. can you please check utilization by each core.
I have compiled a weather forecasting software with openmpi in double precision on Ubuntu 14.04 and Intel ifort compiler. However I am not able to figure out few issues. I need to figure out the number of processors I need to send to mpirun. This is the output of lscpu
x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Thread(s) per core: 2
Core(s) per socket: 2
Socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 60
Stepping: 3
CPU MHz: 800.000
BogoMIPS: 6784.93
Virtualization: VT-x
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 3072K
NUMA node0 CPU(s): 0-3output of lscpu
This is the command that I am using to run my software
mpirun -np 4 aaa. But When I do this I get these errors -
MPI_ABORT was invoked on rank 0 in communicator MPI_COMM_WORLD
with errorcode 1001.
NOTE: invoking MPI_ABORT causes Open MPI to kill all MPI processes.
You may or may not see output from other processes, depending on
exactly when Open MPI kills them.
When I set np to 1 it runs successfully but does not use the CPU completely. CPU usage varies from 3% to 35% but the memory usage is almost 100% and the system freezes for about ten minutes and exits with the error message
forrtl severe(41) insufficient virtual memory.
I have run WRF (the software associated with this question is not WRF) with multiple semaphores and I have not experienced any speed or memory issues.
I could recompile to single precision but before I do that I want to be able to figure out the number of cores(processors) to be sent to mpirun.
Most Intel CPUs (including the one you are using) have a virtual execution unit that allows two simultaneous instruction streams commonly called "hyperthreading." To the Linux kernel, this appears as an extra CPU core. Hence, lscpu tells you there are four CPU cores (CPU(s): 4). Looking carefully at the rest of the output, you will see that there are, in fact, only two CPU cores:
Thread(s) per core: 2 <--- this is hyperthreading
Core(s) per socket: 2
Socket(s): 1
I don't generally recommend running multiple MPI processes on a single physical CPU core even if there is hyperthreading. It tends to lead to detrimental performance, and, in your case, sometimes crashes. Try using mpiexec -np 2 aaa and see what happens. If it crashes again, there is something else wrong.
When I set np to 1 it runs successfully but does not use the CPU completely. CPU usage varies from 3% to 35% but the memory usage is almost 100% and the system freezes for about ten minutes and exits with the error message forrtl severe(41) insufficient virtual memory.
You may need to run a smaller problem size. This machine doesn't have enough physical memory to satisfy the requested allocations and is using virtual memory (essentially hard disk space) to try to fulfill them, but still running out. In any case, you don't want to be using virtual memory when running a simulation (it's ~1000x slower than main memory which is already slow).
I want to know if my program was run in parallel over multiple cores. I can get the perf tool to report how many cores were used in the computation, but not if they were used at the same time (in parallel).
How can this be done?
You can try using the command
top
in another terminal while the program is running. It will show the usage of all the cores on your machine.
A few possible solutions:
Use htop on another terminal as your program is being executed. htop shows the load on each CPU separately, so on an otherwise idle system you'd be able to tell if more than one core is involved in executing your program.
It is also able to show each thread separately, and the overall CPU usage of a program is aggregated, which means that parallel programs will often show CPU usage percentages over 100%.
Execute your program using the time command or shell builtin. For example, under bash on my system:
$ dd if=/dev/zero bs=1M count=100 2>/dev/null | time -p xz -T0 > dev/null
real 0.85
user 2.74
sys 0.14
It is obvious that the total CPU time (user+sys) is significantly higher than the elapsed wall-clock time (real). That indicates the parallel use of multiple cores. Keep in mind, however, that a program that is either inefficient or I/O-bound could have a low overall CPU usage despite using multiple cores at the same time.
Use top and monitor the CPU usage percentage. This method is even less specific than time and has the same weakness regarding parallel programs that do not make full use of the available processing power.
I have 2 quad core processors and I cant seem to understand what "top" is telling me.
I run a VLC transcoding application and i currently transcode 8 streams and "top" shows me that I am using 200% of my CPU. Now for a Pentium 3 that would be horribly bad but I dont understand how Linux calculates CPU usage with multi core processors.
Does this mean that my both processors are utilized 100%? 2 cores at 100%?
I also ran ffmpeg application for the same purpose and I could run 8 instances at 90% each which seemed to me like each processoss would occupy 1 core.
VLC has much lower CPU usage footprint so I just want to make sure I am not killing the hardware.
The output of top stating %cpu = 200 could be that of two cores at 100% or all eight using 25%
Being that you have 2 quadcores the %cpu would range from 0 - 800%