On Sun, 2014-05-18 at 18:35 +0200, Borislav Petkov wrote: > On Sun, May 18, 2014 at 11:05:04PM +0800, Chen Yucong wrote:a > > mces_seen is a Per-CPU variable which should only be accessed by > > Per-CPU as possible. So the clear operation of mces_seen should also > > be lcoal to Per-CPU rather than monarch CPU. > > No, you need to do the cleaning in mce_reign because the monarch cpu has > to run last after all other cpus have scanned their mce banks. > But all other CPUs also have to wait monarch CPU to exit from mce_end. What's the difference between monarch CPU and Per-CPU for clearing mces_seen? In practice, there is no difference between them. If we use monarch CPU to clear mces_seen, then Per-CPU variable can not play out its advantage.
> > Meanwhile, there is also a potential risk that mces_seen will not > > be be cleared if a timeout occors in mce_end for monarch CPU. As a > > reuslt, the stale value of mces_seen will reappear on the next mce. > > If that happens, we have a bigger problem. Well, in that case, why is there a need for time-out machine in MCE handler? Any potential risks --both logical and realistic-- should be avoided as possible if there are no more questions and performance penalty. thx! cyc > > Is that a real issue you're trying to address? -- 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/