On Mon, 2010-11-29 at 15:03 +0800, Huang Ying wrote: > This version of the gen_pool memory allocator supports lockless > operation. > > This makes it safe to use in NMI handlers and other special > unblockable contexts that could otherwise deadlock on locks. This is > implemented by using atomic operations and retries on any conflicts. > The disadvantage is that there may be livelocks in extreme cases. For > better scalability, one gen_pool allocator can be used for each CPU. > > The lockless operation only works if there is enough memory available. > If new memory is added to the pool a lock has to be still taken. So > any user relying on locklessness has to ensure that sufficient memory > is preallocated. > > The basic atomic operation of this allocator is cmpxchg on long. On > architectures that don't have NMI-safe cmpxchg implementation, a > spin_trylock_irqsave based fallback is used for gen_pool_alloc, so it > can be used in NMI handler safely. But gen_pool_free can not be used > in NMI handler in these architectures, because memory free can not > fail. I still don't see a reason to merge this. It makes the genalloc thing slower for every other user (more LOCK'ed ops) and there is no new user presented in this series. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
