FYI, I have filed a bug on our internal bugzilla. Please ping me off list if you want to be cc'd on the report.
Thanks, Peter Peter Linnell SUSE Linux Technical Specialist Tel: 1-415-308-3037 >>> Juha Vuori <[email protected]> 1/14/2013 07:37 AM >>> It's great that there was a clear-cut explanation for our symptoms. Thanks for sharing the information. Really interesting aritmetics.. It is also interesting to know that piece of information about hw architecture differences, about clock registers. It would have been disappointing if zArch clock register had been only twice as good as Intel's, but it turns out it is around 250 times better! :) It really is a privilege to be able to work with zArch machines. When the sw fix is available, even I am willing to shut the birds down just to apply a patch - not for security but for stability... If you can optimize the code even so that the next overflow happens only after 143 years, I have to send a note to my becoming grand-grand-children so that they will remember to take zlnx011 down in _controlled_ way just before the crash would hit... Juha On 14.01.2013 14:11, Heiko Carstens wrote: > On Fri, Jan 11, 2013 at 11:24:41PM +0200, Juha Vuori wrote: >> Hello, >> >> Yesterday, it was 417 days since our currently running z/VM was IPLed. A set >> of four SLES 11.1 >> guests had been alive as long as VM. > > [...] > >> I opened a SR with Novell about zlnx011, and the conclusion was the TID >> http://www.novell.com/support/kb/doc.php?id=7009834 >> ... well, not exactly, but "s390x version" of it. So, I recycled zlnx011, >> and plan to upgrade its >> kernel soon. > > Thanks for bringing this to the list! The mentioned bug fix in the Novell > bugzilla is > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=4cecf6d401a01d054afc1e5f605bcbfe553cb9b9 > > That patch is for x86 only and won't fix your problem. However we do have a > similar bug in the s390 kernel code. The only difference is that it will > indeed trigger after 417 days instead of 208 days. > > The reason is that we calculate with differences of the TOD clock register. > The TOD clock wraps after appr. 143 years. So far no problem... > > However when converting a difference to nanoseconds we must divide the value > by 4.096. Without floating point arithmetics in the kernel we do that by > multiplying with 125 and afterwards dividing by 512... and there you can > see when the overflow happens: > > 143 years / 125 = 1.114 years. And 365 days * 1.114 = 417.56 days. > > So, that's when we hit the overflow. > > We are working on a fix! > > Thanks again for reporting! > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO LINUX-390 or visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
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