Messages in this thread | | | Date | Tue, 4 Feb 2003 09:37:49 -0800 (PST) | From | "Randy.Dunlap" <> | Subject | Re: [PATCH *] use 64 bit jiffies |
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On Tue, 4 Feb 2003, Denis Vlasenko wrote:
| On 3 February 2003 10:28, Matti Aarnio wrote: | > | > You don't need to have 64-bit jiffy for things like internal | > timers, nor for uptime tracking. | > | > Timers have well behaving constructs to use 32-bit jiffy quite | > successfully, and 64-bit values, especially atomicish, in 32-bit | > register-poor machines (i386) are damn difficult. | > | > I do have a number of machines with 100 to 300 day uptimes, all | > with "mere" 32-bit jiffy. With 1000 Hz clock that means at least | > one full wrap-around of jiffy. | | Your processes will show strange start times, CPU times etc. | This will happen in 2.5 pretty soon (after 50 days uptime). | | However, this is a bit cosmetic. There is a much more serious problem: | | Jiffy Wrap Bugs | | There were reports of machines hanging on jiffy wrap. | This is typically a result of incorrect jiffy use in some driver. | Ask Tim - he is hunting those problems regularly, but he is outnumbered | by buggy driver authors. :( | | There is a better solution to ensure correct jiffy wrap handling in | *ALL* kernel code: make jiffy wrap in first five minutes of uptime. | Tim has a patch for such config option. This is almost right. | This MUST NOT be a config option, it MUST be mandatory in every | kernel. Driver writers would be bitten by their own bugs and will | fix it themself. Tim, what do you think?
I like it too. We should take advantage of easy-to-force/find/fix problems like this.
-- ~Randy
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