Messages in this thread | | | From | Petr Tesarik <> | Subject | Re: Serious problem with ticket spinlocks on ia64 | Date | Fri, 3 Sep 2010 16:52:55 +0200 |
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On Friday 03 of September 2010 16:35:23 Petr Tesarik wrote: > On Friday 03 of September 2010 11:04:37 Petr Tesarik wrote: > > [...] > > I'm now trying to modify the lock primitives: > > > > 1. replace the fetchadd4.acq with looping over cmpxchg > > I did this and I feel dumber than ever.
One more thing - the crash dump I got from that run shows that CPU 2 was just going through zap_page_range(), so it probably also did a few global TLB flushes. I'm not sure how this should matter, but any idea is good now, I think.
Anyway, if a global TLB flush is necessary to trigger the bug, it would also explain why we couldn't reproduce it in user-space.
OK, I know I'm just wildly guessing (and don't have any explanation for the wrap-around mystery) ... but does anybody have a better idea?
Petr Tesarik
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