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how to build a simple lock (mutex) on nios II cpu


how to build a simple lock (mutex) on nios II cpu

By : elian epstain
Date : November 29 2020, 09:01 AM
fixed the issue. Will look into that further It appears the Nios II architecture doesn't have atomic test-and-set instructions. Instead for synchronization of shared resources between multiple Nios II processors, the architecture uses an "Hardware Mutex Core". It works as a shared peripheral that provides an atomic test-and-test operation. You can read more about it in Altera's Creating Multiprocessor Nios II Systems Tutorial.
However, you probably don't an atomic test-and-set operation. You can make any sequence of instructions atomic with respect to interrupts on a single core system simply by disabling interrupts.
code :


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how to make a mutex lock among programs, liike mutex lock among processes

how to make a mutex lock among programs, liike mutex lock among processes


By : Muhammad Irfan Malik
Date : March 29 2020, 07:55 AM
With these it helps Your idea of using a lock file is actually a fairly common idiom. It's usually used to make sure that no more than one copy of a program is running at one time. Conventionally the file is named something like ~/.foo_lock or ~/foo/.lock where foo identifies the program.
I don't remember the details of how this is generally implemented, but try man flock for a starting point. I can't recall off the top of my head the name of an open source program that does this. I think however, that gnucash would be such a program, along with numerous mail clients.
c++: spin lock or mutex comparison (simple calculations)

c++: spin lock or mutex comparison (simple calculations)


By : user3433270
Date : March 29 2020, 07:55 AM
this one helps. Spin lock should have better performance than mutex for simple tasks. However, in this simple test (8 threads incrementing a counter), the results shows differently: , some notes:
Why Locking in Go much slower than Java? Lot's of time spent in Mutex.Lock() Mutex.Unlock()

Why Locking in Go much slower than Java? Lot's of time spent in Mutex.Lock() Mutex.Unlock()


By : sumit
Date : March 29 2020, 07:55 AM
To fix this issue I've also posted this question on the golang-nuts group. The reply from Jesper Louis Andersen explains quite well that Java uses synchronization optimization techniques such as lock escape analysis/lock elision and lock coarsening.
Java JIT might be taking the lock and allowing multiple updates at once within the lock to increase performance. I ran the Java benchmark with -Djava.compiler=NONE which gave dramatic performance, but is not a fair comparison.
pthread_mutex_lock waiting to lock a highly contented mutex exactly 60 seconds, if the mutex cant be locked immediately

pthread_mutex_lock waiting to lock a highly contented mutex exactly 60 seconds, if the mutex cant be locked immediately


By : Kiran Yadav
Date : March 29 2020, 07:55 AM
wish of those help The problem was that, I initialized the mutex with DEFAULT_INITIALIZER using this
code :
pthread_mutex_init(&mutex, NULL);
int rc;
pthread_mutexattr_t mattr;
pthread_mutex_t mutex;
rc = pthread_mutexattr_init(&mattr);
if(rc != 0)
   perror("Error occured in mutex attr init");
rc = pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
if(rc != 0)
       perror("Error occured in pthread_mutexattr_setpshared");
pthread_mutex_init(&mutex, &mattr);
Whats better std::lock_guard<std::mutex> lock(std::mutex mutex_var); or std::mutex mutex_var.lock();

Whats better std::lock_guard<std::mutex> lock(std::mutex mutex_var); or std::mutex mutex_var.lock();


By : Paweł Ostrowski
Date : March 29 2020, 07:55 AM
hope this fix your issue You should (almost) never use std::mutex::lock(), std::mutex::try_lock() or std::mutex::unlock() directly, always use a std::lock_guard or std::unique_lock with your mutex_var. Because you don't have to write unlock, because they are doing it when they are destroyed. So you can't forget it, even if a exception has been thrown in the mean time. This is called RAII and is what you want for modern C++ code
So std::lock_guard is better
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