On Fri, Mar 6, 2015 at 12:52 PM, Chris Adams <linux at cmadams.net> wrote:> Once upon a time, Les Mikesell <lesmikesell at gmail.com> said: >> Does anyone have a succinct summary of how to prove to >> management-types that a given linux box won't have a problem with the >> leap second? Like kernel > some_version, tzdata > some_version, >> tzdata-java > some_version? > > Only way to "prove" it is to set up a test and try it.I don't think I need to 'prove' that computer programs do repeatable things. I just want to know the version numbers that need to be installed - something relatively easy to check.> AFAIK there are > no known issues with an up-to-date system,Yeah, but you probably would have said that before the 2012 instance too... And what I really want to know is how 'out-of-date' a system can be.> but that was also true at the > last couple of leap seconds (the issues that happened were previously > unknown).Now we know the issues, and hopefully someone had done the simulation tests. I just want to know the specific kernel and package versions that have the fixes. But none of the links I've found discussing the issues boil it down to something a non-geek would want to see. -- Les Mikesell lesmikesell at gmail.com
Les Mikesell wrote:> On Fri, Mar 6, 2015 at 12:52 PM, Chris Adams <linux at cmadams.net> wrote: >> Once upon a time, Les Mikesell <lesmikesell at gmail.com> said: >>> Does anyone have a succinct summary of how to prove to >>> management-types that a given linux box won't have a problem with the >>> leap second? Like kernel > some_version, tzdata > some_version, >>> tzdata-java > some_version? >> >> Only way to "prove" it is to set up a test and try it. > > I don't think I need to 'prove' that computer programs do repeatable > things. I just want to know the version numbers that need to be > installed - something relatively easy to check.<snip> Two other thoughts: first, that it worked perfectly fine the last leap second, and second, that ntpd, according to the manpage, can and will adjust for seconds of difference with no problem at all, since that's it's job. mark
On Fri, Mar 6, 2015 at 1:50 PM, <m.roth at 5-cent.us> wrote:>> >> I don't think I need to 'prove' that computer programs do repeatable >> things. I just want to know the version numbers that need to be >> installed - something relatively easy to check. > <snip> > Two other thoughts: first, that it worked perfectly fine the last leap > second, and second, that ntpd, according to the manpage, can and will > adjust for seconds of difference with no problem at all, since that's it's > job.Errr, no. It did _not_ work fine in the last leap second. If you run threaded applications (including, but not exclusively, java) or applications that called usleep the kernel would spin with 100% CPU use until you reset the date with some means other than ntp. How could you have missed that: http://www.wired.com/2012/07/leap-second-bug-wreaks-havoc-with-java-linux/. Every other sysadmin in the world got calls in the middle of the night to fix their servers. -- Les Mikesell lesmikesell at gmail.com
Once upon a time, Les Mikesell <lesmikesell at gmail.com> said:> Now we know the issues, and hopefully someone had done the simulation > tests.No, we know the issue that broke last time (2012), and a different issue that broke the time before that (2008) (they were different problems). We don't know any issues that may happen this time, unless you think no bugs have been introduced since the last leap second (obviously hindsight tells us there were between 2008 and 2012). Before the 2012 leap second, I ran tests to make sure the 2008 issue had been fixed, and it had. However, apparently nobody else ran their current setups through tests (maybe also hoping somebody else had done it), so there was a new issue. I haven't actually checked to see that the 2008 issue has remained fixed (it should have, since the code had been changed to move away from that lock all together). My setup wasn't hit by the 2012 issue, so I don't have a simple test for that. So again, if you want to make sure there's no new issue, you'll have to set up a test yourself. I doubt the 2008 or 2012 issues will happen again, but there's plenty of room for new issues. -- Chris Adams <linux at cmadams.net>
On Fri, Mar 6, 2015 at 2:45 PM, Chris Adams <linux at cmadams.net> wrote:> > > So again, if you want to make sure there's no new issue, you'll have to > set up a test yourself. I doubt the 2008 or 2012 issues will happen > again, but there's plenty of room for new issues.So are you saying that you think no one upstream has done any testing yet? Or that I should have better resources for testing than they do? I was hoping things weren't really that bad and that I just hadn't found the simple summary of results yet. -- Les Mikesell lesmikesell at gmail.com