Messages in this thread | | | Date | Tue, 31 Mar 2009 10:08:00 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH -tip 1/3] x86, mce: Add mce_threshold option for intel cmci |
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Hidetoshi Seto wrote: > Andi Kleen wrote: >> To turn it off you would need to disable the CMCI enable bit >> completely. > > mce_threshold=0 discourages CMCI initialization. > The CMCI enable bits are kept in off states in this case.
True, I missed that earlier. Still a different option would be better.
> >> However I expect that this will be not a good idea to ever use on Nehalem >> class systems at least because without CMCI the machine check code cannot >> handle shared banks correctly and you'll get duplicated events from them. >> And on non Nehalem systems there is no CMCI anyways, so it'll be always >> off. > > One question is that even if one clears record in a shared bank, others > sharing the bank still can retrieve same record? Or the duplication of > recored only happens if a shared bank is polled by multiple cpu in parallel > at same time?
Only when multiple CPUs poll (or machine check) at the same time.
> > So old kernel without CMCI support running on new Nehalem class system will > make duplicated records, right?
Occasionally when it races yes.
> Doesn't it impact to current distro like RHEL5?
Yes, somewhat. The bigger problem there is actually lack of broadcast handling, that often leads to incorrect reporting of fatal MCEs.
-Andi
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