Messages in this thread | | | From | "Pan, Zhenjie" <> | Subject | RE: [PATCH v2] NMI: fix NMI period is not correct when cpu frequency changes issue. | Date | Mon, 22 Apr 2013 00:50:34 +0000 |
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> I believe it mattered to the Chrome folks. They want the watchdog to be as > tight as possible so the user experience isn't a hang but a quick reboot > instead. They like setting the watchdog to something like 2 seconds. > > There was a patch a few months ago that tried to hack around this issue and I > suggested this approach as a better solution. I forgot what the original > problem was. Perhaps someone can jump in and explain the problem being > solved (other than the watchdog isn't always 10 seconds)? > > Cheers, > Don
Yes, I also think the period is important sometimes. As I mentioned before, the case I meet is: When the system hang with interrupt disabled, we use NMI to detect. Then it will find hard lockup and cause a panic. Panic is very important for debug these kind of issues.
But if cpu frequency change, the period will be 2 times, 3 times even more.(if cpu can down from 2.0GHz to 200MHz, will be 10 times, it's a very big deviation) This make watchdog reset happen before hard lockup detect.
Thanks Pan Zhenjie
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