Messages in this thread | | | Date | Thu, 2 Apr 2015 10:31:50 -0700 | Subject | Re: smp_call_function_single lockups | From | Linus Torvalds <> |
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On Wed, Apr 1, 2015 at 2:59 PM, Chris J Arges <chris.j.arges@canonical.com> wrote: > > It is worthwhile to do a 'bisect' to see where on average it takes > longer to reproduce? Perhaps it will point to a relevant change, or it > may be completely useless.
It's likely to be an exercise in futility. "git bisect" is realyl bad at "gray area" things, and when it's a question of "it takes hours or days to reproduce", it's almost certainly not worth it. Not unless there is some really clear cut-off that we can believably say "this causes it to get much slower". And in this case, I don't think it's that clear-cut. Judging by DaveJ's attempts at bisecting things, the timing just changes. And the differences might be due to entirely unrelated changes like cacheline alignment etc.
So unless we find a real clear signature of the bug (I was hoping that the ISR bit would be that sign), I don't think trying to bisect it based on how quickly you can reproduce things is worthwhile.
Linus
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