On Wed, Jul 9, 2014 at 12:17 PM, Borislav Petkov <b...@alien8.de> wrote: > > On Wed, Jul 09, 2014 at 10:09:21AM -0700, Havard Skinnemoen wrote: > > From: Ewout van Bekkum <ew...@google.com> > > > > The CMCI poll interval was updated to pick the minimum interval between > > the original 30 seconds and the check_interval divided by 8 (minimum of > > 3 polls). > > Why min 3 polls? How do you come up with exactly that frequency?
The idea is that if we make it equal to check_interval, it might bounce back and forth a lot. So we need to divide by something, and 8 seems like a nice, safe value, and it seems to work well. We're not opposed to considering other values, of course (e.g. 2 and 4 might work well too, but with somewhat higher risk of ping-ponging). > > This resolves a bug where the CMCI storm handler is unable to return to > > interrupt mode from polling mode, if the check_interval shorter than the > > CMCI poll interval. This problem is caused by the mce_timer_fn function > > which only allows the poll interval to be incremented up to the > > check_interval, while the mce_intel_adjust_timer function requires the > > poll interval to be greater than the CMCI poll interval before leaving > > the CMCI_STORM_ACTIVE state. > > Interesting. So it seems you guys want to set the check_interval to > something < 30 secs. > > Out of curiosity, what is your use case which requires such small > check_interval setting? I'm not entirely sure. At some point, it ended up that way, and it broke in non-obvious ways, so we wanted to fix it. > Maybe we need to redesign and simplify this intervals thing to make it > more user-friendly... > > Btw, on a related note, we're working on a small mechanism which > collects correctable errors in the kernel and when a certain count for a > physical error address has been reached, we soft-offline that page. We'd > appreciate it if you guys took a look and told us whether it makes sense > to you: > > http://lkml.kernel.org/r/1404242623-10094-1-git-send-email...@alien8.de We will definitely take a look, thanks. Looks interesting, though it's not always obvious what works for us until we actually go and try it. Havard -- 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/
