Programming :: Which Is Scheduling Algorithm Which Will Make Thread O?
May 4, 2011
I have a timer thread, and when it expires, it sets a flag. The only problem is, if any higher priority thread comes in between, then the timer is not expired in real time.Thus i want to set a highest priority to my thread. Now, i know 2 algos, which can make my thread in real time are: SCHED_FIFO and SCHED_RR.
So, here are my queries: 1) Which scheduling algo is best suited for this purpose? 2) Is it guaranted to work in real time if i use that algo (you suggest in 1) and set the max_priority by getting the maximum settable priority for that particular algorithm using, int sched_get_priority_max(int policy);
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Mar 23, 2010
I have a program which is uses sigaction to register for a SIGIO signal (for incoming data on a fd) with an appropriate event handler. I also create a new detached thread 'B' that does some work with the received data. Normally the thread B runs properly. But when my event handler is called (because a there is new incoming data), after the event is handled, the thread B is not called immediately. There is a noticeable delay of the order of many seconds before it is scheduled again .During this delay, my program is doing nothing.
What am i doing wrong? Is there someway i can run thread B as soon as the event is handled (and assuming no other work is to be carried out)?
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Sep 9, 2009
I am new to thread programming. I need to generate one thread in one process using posix thread. Which scheduling and priority do i need to use? I want to generate the thread with the lowest priority. As i know there are 3 scheduling policy available SCHED_FIFO, SCHED_RR or SCHED_OTHAR.
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May 3, 2011
I want to change linux scheduling algorithm for some of my processes but when I click on processes in ksysguard and click renice project, all of the processes use normal level cpu scheduling. Why is it such a thing and there is no priority?
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Sep 8, 2010
is linux kernel is priority preemptive kernel?if it is. where it is using round robin scheduling algorithm?when processes are scheduled for the processor process will be allocated as which sechudling alogorithm?
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Feb 16, 2010
Kernel: 2.6.24.2
System: Embedded System
I have a process and two threads running in it. Thread1 is my GUI-Thread (using FLTK) and Thread2 is running at the first 10 sec. after start.Now, I would like to make Thread2 "nicer" to Thread1, because otherwise GUI stucks sometimes. But I didn't find a solution.Is it possible to define the "niceness" of threads inside a process (to each other)? And if so, how do I have to do this?
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Jun 13, 2011
Not sure if I have landed in right place for this question .Problem FacedI have 30-40 heavy load (Memory operations on heap) processor running with each having 30-40 threads.In one of the thread (of each process), I have file locking operation as explained below (say in thread T1)Step 1 - Lock the file using fcntl(SETWLK) on file f1, Basically using wait lock.Step 2 - Read/write data from another file f2.Step 3 - unlock the file f1.As the memory occupied by process increased, the swap area used will reduce - this continues for a long amount of period. When the free swap space is reduced to 100 MB free out of 2 G and VIRT reduces to 120MB free out of 17G, for T1 thread, Step 3 is not scheduled for more than 300 seconds after Step 1 and 2.
I want to understand why this behavior is present - as per my understanding scheduling will occur within micro-seconds and we can expect that the T1 thread of all process should be scheduled without too much delay.Additional InfomationMachine Info : (uname -a), Linux linux 2.6.16.46-0.12-smp#1 SMP Thu May 17 14:00:09 UTC 2007 x86_64 x86_64 GNU/LinuxMemory Info :Total Memory is 16GB + Swap Memory is 2GBI want to know why this behavior is observed in SUSE
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Dec 25, 2010
I am going to use "pthread_setaffinity_np" to bind a thread to a specific core. My application has two threads. I have used mutex to assign a specific id to each thread and then bind that thread to a core different from another core. but it seems that the os assigns both thread to one core.What should I do to bind each thread to a specific core?
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Aug 16, 2011
i use SHA-512 algorithm in the /etc/shadow File But i Want to use my lgorithm ..
how i can remove the sha-512 and use my algoritm ? Because no one can des encrypt it !! He Not Know the algorithm method
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Aug 2, 2010
Can I know the implemention of RSA(Encryption and decryption) algorithm in C / C++.
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Apr 27, 2011
I have a copy of the MD5 algorithm and I'm taking a look at the source. It's pretty interesting but there are a few things that I'm curious about and I was wondering if anyone a bit more intuitive than I could help me out.The function declarations in the MD5 files are a bit unfamiliar to me. There is a macro used called PROTO_LIST, which I'm still not sure as to what this thing is doing exactly, but it's littered everywhere throughout the source.The signature here isn't too unfamiliar to me with the exception of the position of the PROTO_LIST macro. So here is a function with an unnamed argument of type MD5_CTX*.To me, this resembles an initializer list found in C++ with constructors but I certainly don't think that is the case here. So my questions about this are (1) how is this legal code in C and (2) what functionality has the PROTO_LIST macro provided for the function?
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Feb 11, 2011
I wrote a code .sh I want to make it a runnable thread.
Q1: How can I do that in Ununtu?
Q2: I put that file (x.sh) in the "Auto start" program.I choose start at "start up" but it open the code editor page.I want it to be run behind backgroun...Have I convert it to .exe firstly ?!
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Feb 25, 2010
Is there a way for members to make a thread with a poll? I've looked around and havent found how, but thought it is around here somewhere.
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Jul 16, 2010
I've got a bit of an obscure question for you to test your brains a wee bit. I'm trying to implement a search program to find areas of high density in a binary string.
E.g.
Code:
[0001001010
0001110001
0000001000
1001000010
0101100100]
Where density is the number of 1's / number of digits with a maximum number of digits being the current number in a buffer (in this example 50). So for the example the density for the whole buffer is 15/50. But the density of Buffer[14..20]=[1110001]=4/7. So if looking for areas of density = 1/3 it would find the longest sequences of density over 1/3.So in the example. Buffer[4..9]=[100101]=3/6=1/2 which is above 1/3 but it is within the Buffer[4..48]=[100101000011100010000001000100100001001011001]=15/45=1/3
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Sep 13, 2010
I have an algorithm guys called "Self Configurable Diagnosis Algorithm" but i don't have program for this.help me regarding that program and which type of Tcl script will be better suitable for that.
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Sep 8, 2010
I have two functions:
Quote:
void func1(std::string &s)
{
s.clear();
}
[code]....
Is there a way to create one template function for both vector and string that would clear them?
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Sep 28, 2010
A simple TCP based chat server could allow users to use any TCP client (telnet, for example) to communicate with each other. For this question you should consider a single process, single thread server that can support exactly 2 clients at once, the server simply forwards whatever is sent from one client to the other (in both directions). Your server must not insist on any specific ordering of messages as soon as something is sent from one client it is immediately forwarded to the other client. As soon as either client terminates the connection the server can exit
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May 3, 2011
I need to simulate dijsktra's algorithm using network animator of ns2. how to write a tcl script for my code. This tcl script runs the dijsktra code and simulates its running on network animator.
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Jun 27, 2011
AStar works on the basis of straight lines, AFAIK. In my case, we have geocoordinates and I can get the straight line distance between the waypoints. But I am wondering how approximate will the route calculated on this basis be? The actual distance "by road", which actually matters can be different.
Example. Assuming A and B are on the same plane, and will be equidistant from the goal point, if we consider a straight line between A and the goal point and, B and the goal point. The distance "by road" between A and the goal point may be greater or lesser than B. But because the AStar works on the basis of straight lines, it will return both the routes as the shortest. If yes, then which algo should be considered , if we want the results on the basis of actual distance in Km/m?
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Feb 25, 2011
i need a program for Encryption and Decryption using RSA algorithm in JAVA ..
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May 2, 2009
i try to understand this algorithm but i cann't. [URL] I encounter problem understand the algorithm of fixed base windowing exponentiation algorithm ? What is fixed base in the first place ? How this algorithm works ?
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Feb 10, 2010
i think we can simulate preemption by using 2 different priority thread, am i true? I just try these scenario :
1. Create Thread A with priority 99 , SCHED_FIFO..
2. Create Thread B with priority 4 , SCHED_FIFO
Thread A started and doing some busy work.. I guess that Thread B wouldn't start until thread A finished, but I get thread B can run before Thread A finished (It just like a common task switching).. I'm sure my 2 thread has right priority. and if thread B is doing some work and if i yield it to thread A, it should preempt it but this doesnt happen, do someone kno wats happening?
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May 10, 2011
Does anyone know how to run 2 threads with round robin scheduling. & can we get the time of these threads when they are context switching. That means I want to know at how much time each thread is taking to run
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May 20, 2010
algorithm:breada
input: file system block number for immediate read
file system block number for asynchronous read
output:buffer containing data for immediate read {
if(first block not in cache) {
get buffer for first block
if(buffer data not valid)
initiate disk read }
if(second block not in cache) {
get buffer for second block)
if(buffer data valid) //line 1
release buffer else
initiate disk read //line 2 }
if(first block was originally in cache) //line 3 {
read first block
return buffer }
sleep (event first buffer contains valid data)
return buffer }
Here is an algorithm for block read algorithm. I have problem in
line 1: If buffer data is valid why is it releasing the buffer?
line 2: If buffer data valid why is it initiating disk read. It should have read directly from buffer?
line 3: It should be the first condition as if it is there in cache then it should return it without delay?
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Apr 2, 2010
Does anyone know of a C Language Data Structure Tutorial? I have not been able to find anything much to speak of myself.
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Jan 9, 2010
The algorithm for reading and writing disk blocks use the algorithm getblk to allocate buffers from the pool. In the algorithm getblk, if the kernel removes a buffer from the free list, it must raise the processor priority level to block out interrupts before checking the free list. Why ?Where can i find the C implementation of the above algorithm for buffer allocation in the linux source code ?
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Jan 12, 2011
I am working on a large program in C to run on Puppy Linux. I have multiple pthreads running. I want to be able to set the pthread SCHED_POLICY and priority in my program but I want a user to be able to run the program without root privilege.
Using a sticky bit and root ownership gives the user too much power because they will be able to write and compile their own scripts. Is there a way to use 'sudo' when I set the thread parameters from my program or something like this?
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Jul 28, 2010
I want to simulate a serial protocol in user space program to test reception algorithm. The protocol is similar to UART protocol but frame format is different. The duration of 1 bit is 114,46 us. In my main function I'm creating two threads. Tx for simulating transmitting data and Rx for reception data. For measure time I use create_timer() function and signals. Each thread has its own timer and signal handler. Tx timer uses SIGUSR1 and Rx timer uses SIGUSR2. Tx thread sets the global variable and Rx reads it.
The timers are set to sample with 114,46 us period. When they reach this value signal handler should set the flag. Flag is check in thread and some operation are made. When I set the timers period for longer time (100 ms) everything works fine but when I change it to default value (114,46 us) the Rx thread doesn't receive the proper data. I am wondering if the 114,46 timer period is possible to simulate in user space? Whether the time will give me the proper resolution ? Theoretically it should provide 1 ns resolution.
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Jun 24, 2010
What is the quickest way to get the thread id(tid) of the current thread in linux? Specifically I use fedora 13. ...and I am talking about inside a C++ program.
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Jul 2, 2010
Is there a library/system call that will return to me what CPU core a thread of execution is running on? I've looked for a bit on the net already and also in /usr/include and couldn't find one.
getcpu() and sched_getcpu() are two that I found, but when I include the appropriate header files (linux/getcpu.h, and sys/sched.h respectively), gcc says getcpu.h doesn't exist and the linker complains it cannot find the implementation in sched.h.
I'm sure I'm doing something really stupid or overthinking...
What I am doing is running an OpenMP application and specifying a list of cpu cores to run on with GOMP_CPU_AFFINITY. I want to make sure that each core is getting the same number of threads.
**UPDATE**
It seems that this code works, but only with glibc >= 2.6, and my machine has 2.5:
Code:
#define _GNU_SOURCE
#include <stdio.h>
#include <utmpx.h>
int main( void )
[Code].....
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