Messages in this thread | | | Subject | Re: [PATCH] perf, x86: catch spurious interrupts after disabling counters | From | Peter Zijlstra <> | Date | Thu, 30 Sep 2010 14:33:38 +0200 |
| |
On Fri, 2010-09-24 at 15:38 +0200, Stephane Eranian wrote: > > I don't like the approach of disabling all counters in the nmi > > handler. First, it stops counting and thus may falsify > > measurement. Second, it introduces much overhead doing a rd-/wrmsrl() > > for each counter. > > > But that's exactly what is going on the Intel side. PMU is stopped on interrupt. > An argument for this is that you don't necessarily want to monitor across > the PMU handler, i.e., the overhead you introduce.
Right, its really a question of what you want to measure. I prefer not to measure the measuring itself, things are hard enough to interpret already.
Then again, the Intel stuff has a real handy way to disable the whole PMU, unlike the AMD bits where you need to iterate each counter individually. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |