Re: Usage semantics of atomic_set ( )
> What operations are you using to implement spinlocks? The cpu provides atomic exchange instruction (atomic Read/write semantics) which forms the back end of spin lock code. __raw_spin_trylock( ) atomically swaps the lock memory with a reg (set to 1) Using a pool of spinlocks rather that original idea of spinlock per atomic_t anyways seems to be a better idea. I really appreciate the responses. Thanks a lot -Vineet -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Usage semantics of atomic_set ( )
What operations are you using to implement spinlocks? The cpu provides atomic exchange instruction (atomic Read/write semantics) which forms the back end of spin lock code. __raw_spin_trylock( ) atomically swaps the lock memory with a reg (set to 1) Using a pool of spinlocks rather that original idea of spinlock per atomic_t anyways seems to be a better idea. I really appreciate the responses. Thanks a lot -Vineet -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Usage semantics of atomic_set ( )
Vineet Gupta wrote: I'm trying to implement atomic ops for a CPU which has no inherent support for Read-Modify-Write Ops. Instead of using a global spin lock which protects all the atomic APIs, I want to use a spin lock per instance of atomic_t. What operations are you using to implement spinlocks? A few architectures use arrays of spinlocks to implement atomic_t. I believe sparc and parisc are among them. Assuming your spinlock implementation is sound and efficient, the same technique should work for you. -- Chris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Usage semantics of atomic_set ( )
> I'm trying to implement atomic ops for a CPU which has no inherent > support for Read-Modify-Write Ops. Instead of using a global spin lock > which protects all the atomic APIs, I want to use a spin lock per > instance of atomic_t. This works well when atomic_t is unitary and > statically initialized using ATOMIC_INIT (where I can reset the > spinlock_t as well). However if atomic_t var is embedded within a > bigger struct which is allocated dynamically how to I init the > embedded spin lock. atomic_set ( ) is the closest choice, however I > don't think it's current usage in kernel code qualifies it to be > "initializer only". A simple way to handle this might be to use a separate array of spinlocks and hash each atomic_t to one entry in the array. You could look in asm-parisc and arch/parisc to see an implementation of this that is already in the kernel. - R. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Usage semantics of atomic_set ( )
I'm trying to implement atomic ops for a CPU which has no inherent support for Read-Modify-Write Ops. Instead of using a global spin lock which protects all the atomic APIs, I want to use a spin lock per instance of atomic_t. This works well when atomic_t is unitary and statically initialized using ATOMIC_INIT (where I can reset the spinlock_t as well). However if atomic_t var is embedded within a bigger struct which is allocated dynamically how to I init the embedded spin lock. atomic_set ( ) is the closest choice, however I don't think it's current usage in kernel code qualifies it to be initializer only. A simple way to handle this might be to use a separate array of spinlocks and hash each atomic_t to one entry in the array. You could look in asm-parisc and arch/parisc to see an implementation of this that is already in the kernel. - R. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Usage semantics of atomic_set ( )
Vineet Gupta wrote: I'm trying to implement atomic ops for a CPU which has no inherent support for Read-Modify-Write Ops. Instead of using a global spin lock which protects all the atomic APIs, I want to use a spin lock per instance of atomic_t. What operations are you using to implement spinlocks? A few architectures use arrays of spinlocks to implement atomic_t. I believe sparc and parisc are among them. Assuming your spinlock implementation is sound and efficient, the same technique should work for you. -- Chris -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
