Re: [Xen-devel] Xen PVM: Strange lockups when running PostgreSQL load

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.10.12 at 09:00, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
>>>> On 17.10.12 at 17:35, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>> In each case, the event channels are masked (no surprise given the
>> conversation so far on this thread), and have no pending events. 
>> Therefore, I believe we are looking at the same bug.
> 
> That seems very unlikely (albeit not impossible) to me, given that
> the non-pvops kernel uses ticket locks while the pvops one doesn't.

And in fact we had a similar problem with our original ticket lock
implementation, exposed by an open coded lock in the scheduler's
run queue management. But that was really ticket lock specific,
in that the fact that a CPU could passively become the owner of
a lock while polling - that's impossible with pvops' byte locks afaict.

Jan


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