Questions tagged [threads]
The threads tag has no usage guidance.
80
questions
0
votes
1answer
46 views
Reason for thread pooling
Can someone explain what is the reason for thread-pooling in Linux, even if the threads are light to create and destroy??
0
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0answers
13 views
Can many threads run in a parallel in many-to-one model?
The book I am reading suggests that in a many-to-one multi-threading model, the threads are unable to run in parallel in a multi-core system.
I am thinking this is not the case because if we have many-...
10
votes
3answers
1k views
Why are most mutex implementations unfair?
My understanding is that most popular implementations of a mutex (e.g. std::mutex in C++) do not guarantee fairness -- that is, they do not guarantee that in instances of contention, the lock will be ...
0
votes
1answer
39 views
Does this lock have a name (related to reader-writer lock)
The object can be locked two different ways, where if the lock is entered the same way a second time, the lock is recursive, but if it's entered the other way, it blocks. Like a reader-writer lock, ...
2
votes
0answers
28 views
What does it mean by “consistent view of memory” in lock-free dequeue implementation?
I am currently reading this paper by Chales-Lev. This paper explain an implementation of work-stealing dequeue. The part where I don't understand is in the implementation of steal operation.
...
1
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0answers
21 views
Parallel Thread Processing Variable Question
if there is a better stack exchange suited for this question please inform me.
say you have a thread that is constantly checking the state of a variable in 2 ms intervals
...
0
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0answers
50 views
Parallel algorithms with desired sequential workload
Could you share any known algorithm which leans on following patterns?
These patterns have both multithreaded and sequential workload. Those algorithms need to be joined to complete some sequential ...
2
votes
1answer
2k views
User level threads are transparent to the kernel?
Find whether given statement True or False? Explain.
User level threads are transparent to the kernel?
My attempt :
False. Since, user level threads are managed by a user level library however, ...
17
votes
4answers
39k views
What threads share in general?
Well this is general question. And if anyone want to make it implementation specific then I will prefer Unix related stuff. But first need to know following problems in generality:
I read single ...
1
vote
1answer
32 views
Why is there no one to many Multithreading Model?
I am studying various multi-threading models. Here the user threads are mapped to Kernel Threads. They are -
...
0
votes
1answer
15 views
multithreading - duration of jobs
" How long will it take for 2 jobs to complete if they're running in parallel, knowing that both have a total of 20 minutes of CPU usage time and 50% IO"
I calculated the CPU usage: ...
0
votes
1answer
32 views
Threads and Operating System
In a computer, the processor executes different threads and changes between them, the operating system is a program at the end that it´s being executed by the processor, there exists the posibility ...
1
vote
1answer
453 views
How can context switch affect the modification of a variable?
float myTotalAmount=0;
void update(float amt){
myTotalAmount+= amt;
}
Task A called update(10);
Calculated ...
3
votes
1answer
59 views
What should be the minimum value when the two threads are executed concurrently
int count=0;
void *thfunc()
{
int ctr=0;
for(ctr=0;ctr<100;ctr++)
count++;
}
If *thfunc() is executed by two threads concurrently in a uniprocessor ...
0
votes
2answers
82 views
Why are threads called the unit of dispatch?
Threads called the "unit of dispatch" but what does that mean? I was looking over the web and two operating systems books but I can't find the answer. It seems that processes are defined by two ...
1
vote
1answer
580 views
About hardware multithreading
I'm reading Multithreading (computer architecture) - Wiki, aka hardware threading, and I'm trying to understand the second paragraph:
(p2): Where multiprocessing systems include multiple complete ...
1
vote
0answers
47 views
How is switching among user-level threads realised in the user space?
This is with respect to user-level threads where the kernel only knows about the process as a whole, and threads are created and maintained in the user space. Each thread has its PC, registers, stack ...
1
vote
0answers
30 views
Definition of PrefixSum function
I came across this paper and attempting to go through the implementation of randomized selection algorithm on page 8.
Step 1 of the algorithm suggest to compute $s = PrefixSum(n_i, p)$. Where $p$ is ...
1
vote
0answers
21 views
User-level threads and information available to the kernel
User-level threads are transparent to the kernel. How is htop able to show user-level threads running on my system? I know that those threads are user-level threads ...
0
votes
1answer
24 views
Can Multiprocessor Systems Implement Both Temporal Multithreading and Simultaneous Multithreading?
I am aware that multiprocessor systems often implement simultaneous multithreading in order to allow multiple threads to run on different CPUs. I am also aware that uni-core systems often implement ...
0
votes
1answer
58 views
What is the Difference Between Many-to-Many (M:M) Threading and Hybrid (M:N) Threading?
I have been researching threading and come across several websites which all say contradicting statements about which and how many thread models exist. Some websites say there are only three: 1:1, M:1 ...
1
vote
0answers
31 views
semaphore for two groups of processes
Can someone help me giving a pseudo code to this problem : There are two groups of processes , A and B. Maximum 3 Processes from group A or group B(only from one group) can use the given resource . ...
3
votes
1answer
94 views
What is the benefit of using one to one thread mapping model instead of Many to Many or two level?
So in the silberschatz O.S book it says Windows uses one to one model (mapping user level threads to kernel level threads)
but why? i thought many to many and two level models are much better, ...
1
vote
2answers
53 views
What is the difference between a page and thread?
"Each process that is executed is divided into blocks of same size, called pages."
"Thread is a part of process being executed."
Are pages and threads both part(s) of process? Whats the difference ...
4
votes
1answer
134 views
What techniques could be used to support thread-local contexts and resources in a language?
I am interested in the subject of thread-local contexts, which is a feature that I use quite often in solutions, but seems to lack first-class support in any languages I have used.
Quite often in ...
1
vote
1answer
114 views
Work-stealing: where and how many to steal
If one ignores the conflicts when accessing the dequeue in Work-Stealing algorithms, does it matter (and in what ways) if one steals from the top or bottom (or anywhere randomly) of the dequeue? Does ...
1
vote
1answer
22 views
Need to understand signals received vs sent
What is meant by in the following statement (from the paper titled "Implementing Lightweight Threads"):
As in singlethreaded processes, the number of signals received by the
process is less than ...
0
votes
1answer
132 views
Hardware thread context and register renaming
I'm having some issues understanding what happens on a context switch with the physical register file in an out-of-order CPU that implements context switching. Suppose that a CPU consists of 4 ...
1
vote
1answer
2k views
What is “time-slice multi-threading”?
My goal is to understand the exact differences between SoEMT, SMT and "time-slice multi threading".
Thus far I already found information on SoEMT and SMT and it does not seem to hard to find more on ...
1
vote
1answer
129 views
Multi-threading : N cores = N times one core?
This question is about modern CPU architectures and multi-threading. I'm mainly interested in personal computers or servers having 2, 4, 8, 16... cores like for example an Intel core i7. I mean not a ...
1
vote
2answers
102 views
What does it mean that a core supports 2 threads?
I understand that a process may have multiple threads, and that a processor may have multiple cores to run processes in parallel.
But I can't understand how a core may allow multiple threads, what ...
1
vote
2answers
5k views
How does RAM is shared in multi core environment?
I learnt that multi core processors have more than one processing units( i.e. the main executing units ALU etc.) and they are better at performance. I want to know how they share Physical memory. I'll ...
2
votes
1answer
273 views
Understanding google's user level threads in kernel threads
I came across Paul Turner work on increasing efficiency of M:N threading model. I am not able to grasp the concept at slide 18 of LPC-User-Threading
It says : for two threads ...
1
vote
0answers
47 views
Is a single starved process considered deadlocked?
In regard to the critical section problem, an algorithm that switches between allowing one of two processes, P1 or P2, to complete their critical section would cause starvation for P1 if P2 stayed in ...
0
votes
0answers
133 views
Algorithm to construct timeline graph with arrival and departure times
So I am trying to construct a timeline graph for threads interacting with synchronization functions e.g. pthread_mutex_lock.
I have the following information:
1- ...
0
votes
1answer
63 views
What do `i` and `Number` represent in the Bakery Algorithm?
I am studying the bakery algorithm, and I am unsure of what the variable i represents in it. I understand that Entering ...
4
votes
1answer
104 views
Is there a generic word for “thread or process”?
I'm writing about a problem that could be caused by race conditions between multiple threads, or OS-level processes on the same machine or different machines, or VM-level processes like the Erlang VM ...
1
vote
0answers
335 views
Do user level threads take advantage of multi processing?
I asked this question here on stackoverflow, but maybe because of off-topic over there, it didn't received proper response.
Does user level threads take advantage of multiprocessing ? I read one such ...
3
votes
1answer
50 views
One rational interval function and one irrational, will they ever collide?
This question may be a little mathy or hardware-y, so I may have to ask elsewhere.
I've recently learned that if a is a positive rational number and b is a positive irrational number, there exists no ...
4
votes
1answer
126 views
Does a reentrant list for signal queue in a single-thread environment exist?
I need to handle Unix signals in a single-threaded application with the following goals:
Signals doesn't mask on receive (thus, the signal handler must be reentrant).
I am not allowed to lose signal ...
5
votes
1answer
146 views
Can threads use resources from other processes?
This is how I see threads. Please do correct me if I'm wrong:
A thread is a part of a process that runs a sequence of program code. There can be many threads within a process that run different ...
0
votes
1answer
1k views
thread scheduling in multi core architecture
In multi core architecture, let us say we have M cores and N threads (N > M) and a process once assigned to a core can't migrate to another core's ready queue. We have to design scheduling policy to ...
2
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0answers
168 views
many to many multithreading
In many to many multithreading model the processor threads are multiplexed to a lesser or equal number of kernel threads.
What exactly does it mean??
Does it mean that if a kernel is executing a ...
2
votes
2answers
2k views
Why there must be a relationship between user threads and kernel threads?
The following is an excerpt from OS concepts by galvin.Here is the book.
Multithreading Models
Our discussion so far has treated threads in a generic sense. However,
support for threads may ...
7
votes
1answer
1k views
Why is quiescent consistency compositional, but sequential consistency is not
I'm having trouble in comparing these two memory consistency models.
Essentially for sequential consistency I think of real code like this:
...
4
votes
1answer
2k views
Difference between IO threads and worker threads
I have read that NodeJs is able to support hundreds and thousand of concurrent calls because the worker threads do not wait on the IO calls to complete. They use event driven IO. Similarly in .NET we ...
1
vote
2answers
2k views
Switching between user-level and kernel-level threads
After reading difference between user-level threads and kernel-level threads ,now I am in doubt of context switching.Context switching is managed by OS when switching between processes/threads but ...
0
votes
1answer
93 views
Is it correct to say that CPU's only compute threads?
New to the world of parallel computation. Would it be correct to say that CPU's are actually thread calculators? My understanding currently: a ...
0
votes
1answer
74 views
What is extra thread for idle time
Here http://tomstechnicalblog.blogspot.com/2016/02/rxjava-understanding-observeon-and.html I've found a sentence which I do not understand:
If you have a quad-core, you can optimally support 5 ...
6
votes
2answers
811 views
Why are multi-threading programs more prone to errors?
Why are multi-threading programs more prone to errors than single threaded programs ? or why is multi-threading programming one of the areas where developers are (more) prone to errors? Is this in ...
