Actually I am doing some self-study and I got stuck in calculating the waiting time of the RR scheduling.
Here is the slide about
RR Scheduling
I am confused by the "Queue" column, at time 6, what's inside the "Queue" is "D<-C". I wonder how this is inferred? If that is the case, then at time 5, the Queue should be "B<-D" instead of a single "B". I'm confused by how to form the Queue.
Thanks for answering!
The way I see it is that a new item in the queue appears when it wants to start to execute.
Look at time 2, there is no B in the queue prior to its execution either.
As the red arrow indicates, D starts (or rather, wants to start) execution at time 6.
Related
I am currently working on analyzing a within-subject dataset with 8 time-ordered assessment points for each subject.
The variables of interest in this example is ID, time point, and accident.
I want to create two variables: accident_intercept and accident_slope, based on the value on accident at a particular time point.
For the accident_intercept variable, once a participant indicated the occurrence of an accident (e.g., accident = 1) at a specific time point, I want the values for that time point and the remaining time points to be 1.
For the accident_slope variable, once a participant indicated the occurrence of an accident (e.g., accident = 1) at a specific time point, I want the value of that time point to be 0, but count up by 1 for the remaining time points until the end time point, for each subject.
The main challenge here is that the process stated above need to be repeated/looped for each participant that occupies 8 rows of data.
Please see how the newly created variables would look like:
I have looked into the instruction for different SPSS syntax, such as loop, the lag/lead functions. I also tried to break my task into different components and google each one. However, I have not made any progress :)
I would be really grateful of any helps and directions that you provide.
Here is one way to do what you need using aggregate to calculate "accident time":
if accident=1 accidentTime=TimePoint.
aggregate out=* mode=addvariables overwrite=yes /break=ID/accidentTime=max(accidentTime).
if TimePoint>=accidentTime Accident_Intercept=1.
if TimePoint>=accidentTime Accident_Slope=TimePoint-accidentTime.
recode Accident_Slope accidentTime (miss=0).
Here is another approach using the lag function:
compute Accident_Intercept=0.
if accident=1 Accident_Intercept=1.
if $casenum>1 and id=lag(id) and lag(Accident_Intercept)=1 Accident_Intercept=1.
compute Accident_Slope=0.
if $casenum>1 and id=lag(id) and lag(Accident_Intercept)=1 Accident_Slope=lag(Accident_Slope) +1.
exe.
Given the variable 'points' which increases every time a variable 'player' collects a point, how do I logically find a way to reward user for finding 30 points inside a 5 minutes limit? There's no countdown timer.
e.g player may have 4 points but in 5 minutes if he has 34 points that also counts.
I was thinking about using timestamps but I don't really know how to do that.
What you are talking about is a "sliding window". Your window is time based. Record each point's timestamp and slide your window over these timestamps. You will need to pick a time increment to slide your window.
Upon each "slide", count your points. When you get the amount you need, "reward your user". The "upon each slide" means you need some sort of timer that calls a function each time to evaluate the result and do what you want.
For example, set a window for 5 minutes and a slide of 1 second. Don't keep a single variable called points. Instead, simply create an array of timestamps. Every timer tick (of 1 second in this case), count the number of timestamps that match t - 5 minutes to t now; if there are 30 or more, you've met your threshold and can reward your super-fast user. If you need the actual value, that may be 34, well, you've just computed it, so you can use it.
There may be ways to optimize this. I've provided the naive approach. Timestamps that have gone out of range can be deleted to save space.
If there are "points going into the window" that count, then just add them to the sum.
Given n processes with their burst times and arrival times, the task is to find average waiting time and average turn around time using scheduling algorithms like FCFS, Round Robin, Shortest remaining time, etc.,
I am very much confused in selecting a Data Structure to implement these algorithms. I implemented using a separate array for each attribute, but the thing it is tedious and we need to write a lot of statements in c. I am thinking of a linked list which each node represents the all attributes. Is it a efficient one. Can you please suggest me a efficient data structure so that search and sorting will be easier.
First, create a data structure to contain the "impossible to know in practice" information about each process (start time, burst time, etc), add a "process state" field (to keep track of "not started, started or stopped"), and add a single "next" field to the structure; then create an array of these structures and fill in the information.
Next create a general purpose function to find the "not started" process that has the earliest start time.
For round robin; find the "not started" process that has the earliest start time, set "current time = first process start time", and set the process' "next" field to point to itself so that you have a circular linked list of one entry, and change the state of the process from "not started" to "started". Then find out which event happens next (will another process start and get added to the circular linked list before a task switch happens?) and handle that event (while advancing your "current time").
For FCFS it's similar to round robin, except you don't bother having task switches until the currently running task stops (and could use a non-circular list instead of a circular list).
For shortest remaining time, it's the same as FCFS except that when a process is started you use "remaining time" to figure out where to insert it into the list.
I have a set of jobs with execution times (C1,C2...Cn) and deadlines (D1,D2,...Dn). Each job will complete its execution in some time, i.e,
response time (R1,R2,....Rn). However, there is a possibility that not every job will complete its execution before its deadline. So I define a variable called Slack for each job, i.e., (S1,S2,...Sn). Slack is basically the difference between the deadline and the response time of jobs, i.e.,
S1=D1-R1
S2=D2-R2, .. and so on
I have a set of slacks [S1,S2,S3,...Sn]. These slacks can be positive or negative depending on the deadline and completion time of tasks, i.e., D and R.
The problem is I need to define weights (W) for each job (or slack) such that the job with negative slack (i.e., R>D, jobs that miss deadlines) has more weight (W) than the jobs with positive slack and based on these weights and slacks I need to define an objective function that can be used to maximize the slack.
The problem doesn't seem to be a difficult one. However, I couldn't find a solution. Some help in this regard is much appreciated.
Thanks
This can often be done easily with variable splitting:
splus(i) - smin(i) = d(i) - r(i)
splus(i) ≥ 0, smin(i) ≥ 0
If we have a term in the objective so that we are minimizing:
sum(i, w1 * splus(i) + w2 * smin(i) )
this will work ok: we don't need to add the complementarity condition splus(i)*smin(i)=0.
I am trying to shape a JMeter test involving a Concurrency Thread Group and a Throughput Shaping Timer as documented here and here. the timer is configured to run ten ramps and stages with RPS from 1 to 333.
I want to set up the Concurrency Thread Group to use the schedule feedback function and added the formula in the Target concurrency field (I have updated the example from tst-name to the actual timer name). ramp-up time and steps I have set to 1 as I assume the properties are not that important if the throughput is managed by the timer; the Hold Target Rate time is 8000, which is longer than the steps added in the timer (6200).
When I run the test, it ends without any exceptions within 3 seconds or so. The log file shows a few rows about starting and ending threads but nothing alarming.
The only thing I find suspicious is the Log entry "VirtualUserController: Test limit reached, thread is done plus thread name.
I am not getting enough clues from the documentation linked here to figure this out myself, do you have any hints?
According to the documentation rampup time and steps should be blank:
When using this approach, leave Concurrency Thread Group Ramp Up Time and Ramp-Up Steps Count fields blank"
So your assumption that setting them to 1 is OK, seems false...