What is the main disadvantage of spinlock?
The primary disadvantage of a spinlock is that, while waiting to acquire a lock, it wastes time that might be productively spent elsewhere. There are two ways to avoid this: Do not acquire the lock.
Can spinlock be interrupted?
@mousey: Someone shares a spin lock with an interrupt handler if they access the same shared data that the interrupt handler does. Mutexes cannot disable interrupts, since if you disable interrupts and sleep, you will never wake up!
When should you spinlock?
SpinLock are typically used when working with interrupts to perform busy waiting inside a loop till the resource is made available. SpinLock don’t cause the thread to be preempted, rather, it continues to spin till lock on the resource is released.
What is difference between spinlock and mutex?
Spinlock is a lock which causes a thread trying to acquire it to simply wait in the loop and repeatedly check for its availability. In contrast, a mutex is a program object that is created so that multiple processes can take turns sharing the same resource. Thus, this is the main difference between spinlock and mutex.
Does spinlock disable preemption?
spinlock automatically disables preemption, which avoids deadlock caused by interrupts. when data is shared with interrupt handler, before holding spinlock we must disable interrupts. when data is shared with bottom halves, before holding spinlock we must disable bottom halves.
What is the difference between preemption and interruption?
As nouns the difference between interruption and preemption is that interruption is the act of interrupting, or the state of being interrupted while preemption is the purchase of something before it is offered for sale to others.
How to disable preemption in Linux spinlocks?
The __raw_spin_lock function looks: As you may see, first of all we disable preemption by the call of the preempt_disable macro from the include/linux/preempt.h (more about this you may read in the ninth part of the Linux kernel initialization process chapter). When we unlock the given spinlock, preemption will be enabled again:
How are spinlocks represented in the Linux kernel?
The spinlock is represented by the spinlock_t type in the Linux kernel. If we will look at the Linux kernel code, we will see that this type is widely used. The spinlock_t is defined as:
Why do I keep getting spinlocks on my computer?
The first reason is that while we’re spinning like this, we appear to the CPU and to the OS like a very busy thread and we will never be moved out of the way. So if the thread that has the lock is not currently running, we could be blocking it from running, causing it to not give up the lock.
Where is the arch spin lock macro in Linux?
The arch_spin_lock macro is defined in the include/asm-generic/qspinlock.h header file as the following: We stop here for this part. In the next part, we’ll dive into how queued spinlocks works and related concepts. This concludes the first part covering synchronization primitives in the Linux kernel.