Russ, On Thu, Oct 19, 2006 at 03:57:20PM -0500, Russ Anderson wrote: > Stephane Eranian wrote: > > > > Yes, it could work for very simple measurements. The CPU_CYCLES is a good example, though > > the event on Montecito as a different name (by same encoding). But it gets more tricky as soon > > as you try accessing PMU registers outside the range of architected registers, i.e., outside > > PMC4-7/PMD4-7. There there are big differences. Montecito has 12 counters, Madison has 4. > > All the extended features, such as opcode matching, range restrictions use differnet registers > > between the 2 models. > > > > Perfmon detects the cpu type using cpuid only once during initialization. So it depends > > on which CPU executes the initialization. The only common set guaranteed to work the same > > way is PMC4-7/PMD4-7 and events CPU_CYCLES and INSTRUCTION_RETIRED. > > Stephane, > > Attached is a test patch for supporting mixed CPUs. It changes pmu_conf to > an array, to keep track of the different CPU characteristics. At initialization > information is saved for each of the CPUs. > I don't think this is going to work for the simple reason that perfmon supports per-thread monitoring. As a thread migrates from one CPU to another, its PMU state migrates with it. So you cannot reload a full Montecito state onto a Madison PMU. You will not crash, because write to unimplemented PMD are ignored but you will get false results. Even in system-wide tools are not prepare to cope with mixed configurations. As I said earlier, in the initialization, you need to detect mixed configuration and if so use the generic IA-64 PMU description on ALL CPUs. This is the one implemented by pmu_conf_gen coming from perfmon_generic.h. -- -Stephane - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|