Jmp logistic regression code#

IntВ pthread_mutex_timedlock(pthread_mutex_tВ *restrictВ mutex,В constВ structВ timespecВ *restrictВ abs_timeout) Two гЂЃ spinlocks 1гЂЃ Introduction to spin lock IntВ pthread_mutex_trylock(pthread_mutex_tВ *mutex) IntВ pthread_mutex_lock(pthread_mutex_tВ *mutex) Pthread_mutex_tВ mutexВ =В PTHREAD_MUTEX_INITIALIZER IntВ pthread_mutex_init(pthread_mutex_tВ *restrictВ mutex,В constВ pthread_mutexattr_tВ *restrictВ attr) IntВ pthread_mutex_destroy(pthread_mutex_tВ *mutex) If the time slice allocated by the thread holding the mutex ends, Thread is dispatched, Other threads waiting for the same mutex need to wait longer. Low priority threads can obtain mutexes, So it blocks high priority threads that need the same mutex. пј€1пј‰ Waiting for mutexes takes time, Waiting delay can damage the scalability of the system. Mutex is actually count=1 Cases of semaphore.

Jmp logistic regression code#

At any moment, Only one thread is allowed into the code protection. Mutex prevents multiple threads from entering the protected critical area of code at the same time пј€critical sectionпј‰. ДЇutex The core idea is to compete most of the time lock The operation is put in the user space, Instead of expensive kernel system calls to execute, So it improves efficiency. Except for a few cases where multiple threads compete for locks at the same time, be based on futex Of lock Operations do not require expensive system calls. In most cases, multiprocessing or multithreading is necessary for futex To operate on an integer variable ( Assembly language calls CPU Atomic operation instructions provided to increase or decrease ), In other cases, it is necessary to operate the waiting queue in the kernel space through expensive system calls ( Wake up the waiting process / Thread or the current process / The thread is put into the waiting queue ). Watson research center пј‰,Matthew Kirkwood,Ingo Molnarпј€Red Hatпј‰ and Rusty Russellпј€IBM Linux Technology Center пј‰ Et al.ДЇutex It consists of an aligned integer variable in user space and a kernel space waiting queue attached to it. ДЇutex It's a Linux Implement locking and build high-level Abstract locks such as semaphores and POSIX The basic tool of mutual exclusion. Linux Kernel 2.6.x The stable version starts ,Linux All of the mutexes are futex (FastВ UsermodeВ Mutex) lock. Mutex belongs to sleep-waiting Type lock.