On Fri, May 24, 2013 at 11:35:15AM +0300, Alexey Suslikov wrote: > Hi tech@. > > Are uvideo(4), bktr(4) and similar also MP safe or they somewhat different > in terms of a technique used to make audio MP safe?
They are mp safe since they use the global kernel_lock; It's used for everything, including interrupts. Basically this makes things worse on MP systems than they are on SP systems. Audio slightly different; cpu-intensive code is being moved to user-space (preemptive, no explicit locking required). Interrupt handlers (the most "sensive" code paths) don't need the kernel_lock anymore, but still they are being delayed by other subsystems because of side effects I don't understand yet. This is being worked on. Syscall code-paths still take the kernel_lock. -- Alexandre
