Calculating CPU Utilization with 5 Processes & 30% I/O Time

[zak100]

Mod note: Initially posted in a non-HW forum section, so missing the template
Summary:: Hi,
I am trying to find CPU utilization

What is the CPU utilization if there are 5 processes running at the same time, and on average the CPU spends 30% of its time waiting on I/O completion?

The formula is :

The formula for CPU utilization is 1−pn, in which n is number of process running in memory and p is the average percentage of time processes are waiting for I/O.

What is P in this formula?: 1-P ^n
I found a solution which finds the CPU utilization for each process separately.
Can we do it in the following way:
1- (0.3)^5
= 0.9975

Is the above answer correct?
Somebody please guide me. Zulfi.

 

[sysprog]

It's not that simple. Performance management is its own whole discipline. Generally in a CPU set the IO processor(s) may be viewed as distinct from the MMU (memory management unit(s)) and from the ALU (arithmetic and logical unit(s)), but there's still communication between them, and you have to measure based on specific processes.

 

[Mark44]

Summary:: Hi,
I am trying to find CPU utilization

What is the CPU utilization if there are 5 processes running at the same time, and on average the CPU spends 30% of its time waiting on I/O completion?

The formula is :

The formula for CPU utilization is 1−pn, in which n is number of process running in memory and p is the average percentage of time processes are waiting for I/O.

What is P in this formula?: 1-P ^n

What is the formula you're working with? In what you quoted, it has $1 - pn$. Just above you have $1 - P^n$.

I found a solution which finds the CPU utilization for each process separately.
Can we do it in the following way:
1- (0.3)^5
= 0.9975

Is the above answer correct?
Somebody please guide me. Zulfi.

You attached an image, but I am not able to view it.

Also, this is a homework question, so should be posted in the Eng. & Comp Sci Homework section. I am moving to that forum section, but in future homework questions, please post them in that section.

 

[zak100]

Hi,
Please provide the link where you have moved the question.

Zulfi.

 

[Mark44]

Please provide the link where you have moved the question.
Zulfi.

The link was there for 1 day, Apparently you figured out where to look for your moved post.

From my post last Thursday...

What is the formula you're working with? In what you quoted, it has $1 - pn$. Just above you have $1 - P^n$.

You attached an image, but I am not able to view it.

 

[zak100]

Hi,
Okay I would know about the link, once I get any reply.

Zulfi.

 

[Mark44]

Enough about the link.

How about the questions I asked? It's not clear what you need to do, since you have two different formulas, and an uploaded image that was blank.

 

[zak100]

Sorry, I don't have any clue for the image. I don't know who did that. I have to change my password. I don't use such numbers for images.

Hope you would now provide me the link.

Zulfi.

 

[Mark44]

Sorry, I don't have any clue for the image. I don't know who did that. I have to change my password. I don't use such numbers for images.

The original post, which was moved by @berkeman, had an image link in it. I don't see that link any longer. Possibly the image was just the part that is quoted in post #1, that follows "The formula is:"

Hope you would now provide me the link.

Let's forget about the image link.

For the third time...

What is the formula you're working with? In what you quoted, it has $1 - pn$. Just above you have $1 - P^n$.

Right now, this is all I'm concerned with.
Is the formula $1 = pn$ or is it $1 - P^n$?

 

[sysprog]

Is the formula $1 = pn$ or is it $1 - P^n$?

Inside the math.stackexchange post by "snr - Reinstate Monica" that @zak100 without attribution quoted, it's $1-P^n$ -- the google preview that he also quoted drops the superscript. The original post is here: https://math.stackexchange.com/questions/3178567/calculation-of-cpu-utilization-problem