My application file alters the TX power using two different algorithms, will call them algorithm1 and algorithm2.
I do four separate runs as follows:
1) Simulate for 400 seconds, alter TXPOWER using algorithm 1. At the end I would have simulated n vehicles.
2) Simulate for 400 seconds, alter TXPOWER using algorithm 2. At the end I would have simulated m vehicles.
3) Simulate for 50 seconds, alter TXPOWER using algorithm 1. At the end I would have simulated x vehicles.
4) Simulate for 50 seconds, alter TXPOWER using algorithm 2. At the end I would have simulated y vehicles.
I noticed that for run 1 and run 2 I would have n <> m
and for run 3 and run 4 I would have x = y
where n,m,x,y are the numbers of vehicles simulated for run 1,2,3,4 respectively.
The question is, I do not understand why that the first two runs i have n <> m and for the latter two runs I have x = y
Thank you.
Related
I'm studying for a uni project and one of the requirements is to include multithreading. I decided to make a prime number finder and - while it works - it's rather slow. My best guess is that this has to do with the amount of threads I'm creating and destroying.
My approach was to take the range of primes that are below N, and distribute these evenly across M threads (where M = number of cores (in my case 8)), however these threads are being created and destroyed every time N increases.
Pseudocode looks like this:
for each core
# new thread
for i in (range / numberOfCores) * currentCore
if !possiblePrimeIsntActuallyPrime
if possiblePrime % i == 0
possiblePrimeIsntActuallyPrime = true
return
else
return
Which does work, but 8 threads being created for every possible prime seems to be slowing the system down.
Any suggestions on how to optimise this further?
Use thread pooling.
Create 8 threads and store them in an array. Feed it new data each time one ends and start it again. This will prevent them from having to be created and destroyed each time.
Also, when calculating your range of numbers to check, only check up to ceil(sqrt(N)) as anything after that is guaranteed to either not go into it or the other corresponding factor has already been checked. i.e. ceil(sqrt(24)) is 5.
Once you check 5 you don't need to check anything else because 6 goes into 24 4 times and 4 has been checked, 8 goes into it 3 times and 3 has been checked, etc.
I have two raspberry pi. Suppose this two pi are denoted as A and B
So A and B are connected with each other over socket.
On particular event, A is generating value every one seconds.
and on event A stops generating those values.
So B needs to read those values from A every 1 second over socket.
So B has while loop running
So what I have done is that I am reading time every while loop iteration and checking whether 1 seconds elapsed or not. If 1 seconds elapsed, I am reading values from B.
Here is some pseudo code for this.
while True:
on = read_from_A()
if on: // "on" will suggest me to start read from B
current_time = time.time()
if current_time - last_time == 1:
read_values_from_A()
last_time = current_time
do_some_task()
With this approach I am not able to read read values from A exact after 1 seconds. B is missing some values from A.
So suppose A generated 360 values in 6 minutes
B should be able to read those 360 values.
What is the way that I should be using so that there should not be any data loss.
I am working on a game where I need an algorithm to vary a value in a loop. I have implemented the algorithm but I guess its not working as I want it to work. Here's what I want and what I have already implemented :
Given :
a commodity whose price I want to circulate (from min to max to min again and continuously in a loop)
I am using cocos2d-x (C++) where I have a scheduler which runs a function at a given interval say SCHEDULE_INTERVAL
MIN_PRICE and MAX_PRICE of the commodity
currentPrice
Time duration which it will take to complete one cycle (min-max-min)
Current Implementation :
SCHEDULE_INTERVAL = 0.3 (sec) (so the function is running every 0.3 secs)
counter = 0;
timeDuration = time to complete one cycle
function
{
counter++;
_amplitude = (maxPrice - minPrice)/2;
_midValue = (maxPrice + minPrice)/2;
currentPrice = _midValue + _amplitude * sin (2*PI*counter/timeDuration)
}
why i am using sine wave : because at the peaks i want to make the transitions slow.
Problem : for some reasons its not behaving the way I want it to behave
I want to continuously change the currentPrice form minPrice-maxPrice-minPrice in timeDuration and the loop running at SCHEDULE_INTERVAL
please suggest any solutions.
Thanks :)
EDIT :
what's not working in the above implementation is that the values are not changing according to the 'timeDuration' variable
If the pseudocode you posted accurately mirrors the expressions you use in real code, you probably want to change the argument of sin to this:
2 * PI * (counter * SCHEDULE_INTERVAL) / timeDuration
counter is the number of executions, while timeDuration is (I presume) the desired length in seconds.
In other words, your units don't match - it's always worthwhile to perform a dimensional analysis when formulae don't work.
I have an upper triangular matrix and the result vector b.
My program need to solve the linear system:
Ax = b
using the pipeline method.
And one of the constraints is that the number of process is smaller than the number of
the equations (let's say it can be from 2 to numberOfEquations-1).
I don't have the code right now, I'm thinking about the pseudo code..
My Idea was that one of the processes will create the random upper triangular matrix (A)
the vector b.
lets say this is the random matrix:
1 2 3 4 5 6
0 1 7 8 9 10
0 0 1 12 13 14
0 0 0 1 16 17
0 0 0 0 1 18
0 0 0 0 0 1
and the vector b is [10 5 8 9 10 5]
and I have a smaller amount of processes than the number of equations (lets say 2 processes)
so what I thought is that some process will send to each process line from the matrix and the relevant number from vector b.
so the last line of the matrix and the last number in vector b will be send to
process[numProcs-1] (here i mean to the last process (process 1) )
than he compute the X and sends the result to process 0.
Now process 0 need to compute the 5 line of the matrix and here i'm stuck..
I have the X that was computed by process 1, but how can the process can send to himself
the next line of the matrix and the relevant number from vector b that need to be computed?
Is it possible? I don't think it's right to send to "myself"
Yes, MPI allows a process to send data to itself but one has to be extra careful about possible deadlocks when blocking operations are used. In that case one usually pairs a non-blocking send with blocking receive or vice versa, or one uses calls like MPI_Sendrecv. Sending a message to self usually ends up with the message simply being memory-copied from the source buffer to the destination one with no networking or other heavy machinery involved.
And no, communicating with self is not necessary a bad thing. The most obvious benefit is that it makes the code more symmetric as it removes/reduces the special logic needed to handle self-interaction. Sending to/receiving from self also happens in most collective communication calls. For example, MPI_Scatter also sends part of the data to the root process. To prevent some send-to-self cases that unnecessarily replicate data and decrease performance, MPI allows in-place mode (MPI_IN_PLACE) for most communication-related collectives.
Is it possible? I don't think it's right to send to "myself"
Sure, it is possible to communicate with oneself. There is even a communicator for it: MPI_COMM_SELF. Talking to yourself is not too uncommon.
Your setup sounds like you would rather use MPI collectives. Have a look at MPI_Scatter and MPI_Gather and see if they don't provide you with the functionality, you are looking for.
I work with SoapUI project and I have one question. In following example I've got 505 requests in 5 seconds with thread count =5. I would like to understand how count has been calculated in this example.
For example, if I want 1000 request in 1 minute what setting should I set in variance strategy?
Regards, Evgeniy
variance strategy as the name implies, it varies the number of threads overtime.Within the specified interval the threads will increase and decrease as per the variance value, thus simulating a realistic real time load on target web-service.
How variance is calculated : its not calculated using the mathematical variance formula. its just a multiplication. (if threads = 10 and variance = 0.5 then 10 * 0.5 = 5. The threads will be incremented and decremented by 5)
For example:
Threads = 20
variance = 0.8
Strategy = variance
interval = 60
limit = 60 seconds
the above will vary the thread by 16 (because 20 * 0.8 = 16), that is the thread count will increase to 36 and decrease to 4 and end with the original 20 within the 60 seconds.
if your requirement is to start with 500 threads and hit 1000 set your variance to 2 and so on.
refrence link:
chek the third bullet - simulating different type of load - soapUI site
Book for reference:
Web Service Testing with SoapUi by Charitha kankanamge