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Linux: Maximum CPU Load

Posted on 2014-01-07
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Last Modified: 2014-01-14
My Linux server is reporting 1.2 as its CPU Load.   How can I find out what the maximum number for the CPU load would be?
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Question by:hankknight
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by:farzanj
farzanj earned 20 total points
ID: 39763119
You need to understand what the load is.
Here's a good link
http://blog.scoutapp.com/articles/2009/07/31/understanding-load-averages

Also remember that if your system have more CPU's and/or cores, the load number totally depends on it.

So if you have multiple cores/ CPUs, you are completely fine with 1.25 load average.

Generally it is 1 per core or CPU.
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by:Duncan Roe
Duncan Roe earned 40 total points
ID: 39763344
You can make the load average arbitrarily large by starting a process that runs enough simultaneous threads. E.g. make -j7 in the Linux source directory will ramp the load average up to 7. As long as %id in top is nonzero, you still have CPU power to spare. Watch %wa (wait) - this is the time when no work can be done because of waiting for a disk transfer to finish.
Most important: is response time acceptable?
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by:mohansahu
mohansahu earned 220 total points
ID: 39764578
Hi,

Please find the below link for CPU load and utilization

http://www.cyberciti.biz/tips/how-do-i-find-out-linux-cpu-utilization.html

MS
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by:hankknight
ID: 39765189
How can I find out the total number of available processors and cores?  This should be the maximum CPU Load.   Is there a way from the Linux command line to detect the number of available processors and cores so I can know what the highest potential CPU load could be?
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by:farzanj
ID: 39765196
You can issue command
top

Open in new window


And then hit key '1'

Or use command

dmidecode processor

Open in new window


Or
cat /proc/cpuinfo

Open in new window

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by:mohansahu
mohansahu earned 220 total points
ID: 39766176
1 . To find the number of physical CPUs:
$ cat /proc/cpuinfo | grep "^physical id" | sort | uniq | wc -l

2.To find the number of cores per CPU:
cat /proc/cpuinfo | grep "^cpu cores" | uniq

3.To find the total number of processors:

cat /proc/cpuinfo | grep "^processor" | wc -l

MS
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comfortjeanius earned 200 total points
ID: 39766208
The nproc command shows the number of processing units available:
nproc

Open in new window


lscpu gathers CPU architecture information :
lscpu

Open in new window


or you could use this....
dmidecode -t 4 | grep CPU

Open in new window


Information in the /proc/cpuinfo
cat /proc/cpuinfo  | grep processor

Open in new window


cat /proc/cpuinfo | grep "physical id" | sort | uniq | wc -l

Open in new window

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by:Duncan Roe
Duncan Roe earned 40 total points
ID: 39766397
The load average can go way over the number of CPUs or cores with no ill effects. I've looked into precisely what it means at some length in the past, but not come to any useful conclusion (except that you can make it as high as you like as per http:#a39763344).
Mainly it just scares people. Ignore it and concentrate on real measures like time to accomplish work.
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by:serialband
serialband earned 20 total points
ID: 39767323
The load average can go way over the number of CPUs or cores with no ill effects.

That hasn't been my experience.   If the load average is too far above the number of CPU cores the system does slow down and becomes quite unresponsive.  If it's a short one minute spike, it's not a big deal.  If you run parallel compute clusters that run for hours and days, you can't really run it above the number of CPUs.  It can go a little bit above the number of CPU cores or threads, but then processes slow down.

Load averages are ballpark figures, but I kept them equal to the number of CPU for optimal compute speeds on the parallel compute clusters I ran.
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