On Wed, 2012-09-12 at 18:42 +0200, Stephane Eranian wrote: > We use FREEZE_LBR_ON_PMI to sync LBR data with counter overflows. > That means, LBR is already frozen by the time we get to the handler. But > that means we need to re-enable LBR when we leave the handler. I don't > think EOI is going to magically re-enable it. So we need to touch DEBUGCTL > in the irq handler.
Ah, so I do think EIO will re-enable LBR, also the handler is wrapped in x86_pmu::{dis,en}able_all() which does end up calling intel_pmu_lbr_{dis,en}able_all(). However that leaves the MSR in the exact same state on exit as it was on enter, so that's not a problem for the: read-modify-write change. Its just that the x86_pmu::disable() for the throttle could leave the MSR in a different state on exit than it entered with. This patch avoids that. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/