On Thu, Jul 10, 2014 at 10:51 AM, Havard Skinnemoen <[email protected]> wrote: > What's the typical interrupt rate during a storm? We should make it > significantly less frequent than that, otherwise there's no point > switching to polling. > > IIRC we've seen at least several hundred CMCIs per second, so perhaps > 100 ms would be a reasonable minimum? Or perhaps 10 ms, which is the > current minimum polling interval enforced by mce_timer_fn.
I don't think we have a solid point to really declare "storm!". The CMCI rates between normal and abnormal rates are vast: Normal rates are a few CMCI per year (or maybe per month ... if you have a multi-terabyte machine perhaps even "per day" is normal). So if you see two CMCI inside the same minute, you could declare a storm. Realistically we want the threshold a bit higher. It then becomes a balance between seeing all the errors (so our PFA mechanisms get enough data to spot bad pages and take action) and processing so many interrupts that we begin to take a performamce hit. Once we do decide there is a storm - we know we have given up on seeing all the errors ... the polling rate will only decide how fast we can determine that the storm has ended. I don't see a lot of value in detecting the end at milli-second granularity. But we probably don't want to give up minutes worth of PFA data if the storm does end. -Tony -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
