From: Daniel Hellstrom <daniel@xxxxxxxxxxx> Date: Tue, 26 Oct 2010 19:50:36 +0200 > The LEON do not have internal timers as some CPUs does, it has > one/multiple General Purpose TIMERs on the Processor Local Bus. On > single-CPU/SMP systems the first Timer is used for System Clock, and > on SMP systems timer two is also used to generate a simultaneous IRQ > on all CPUs for profiling etc. (leon_percpu_timer_interrupt()). On the > quad-core SMP system I discovered that since the per-cpu timer is > generated at the same frequency (and almost simultaneously) as the > System Clock Timer. I have made a patch that uses only one Timer for > SMP systems, the Timer generates a per-cpu tick as before, however on > CPU0 the handler_irq() is also called after profiling has been done, > this is to handle the System Clock Tick. I seems to work successfully, > and it saves me HZ interrupts per second and a Timer instance. What is > you opinion about that? Is it possible to use the same timer for > System Clock and for per-cpu profiling etc.? You only need to generate one timer interrupt per-cpu, and the kernel generically decides to run the global timer actions (jiffies update, etc.) on a choosen cpu, transparently, in the per-cpu periodic timer code. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
