[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] xen/arm: Domain not fully destroyed when using credit2
On Tue, 2017-01-24 at 10:50 +0000, Julien Grall wrote: > On 24/01/2017 08:20, Jan Beulich wrote: > > > > > On 23.01.17 at 20:42, <julien.grall@xxxxxxx> wrote: > > > The function domain_destroy will setup the RCU callback > > > (complete_domain_destroy) by calling call_rcu. call_rcu will add > > > the > > > callback into the RCU list and then will may send an IPI (see > > > force_quiescent_state) if the threshold reached. This IPI is here > > > to > > > make sure all CPUs are quiescent before calling the callbacks > > > (e.g > > > complete_domain_destroy). In my case, the threshold has not > > > reached and > > > therefore an IPI is not sent. > > > > But wait - isn't it the nature of RCU that it may take arbitrary > > time > > until the actual call(s) happen(s)? > > Today this arbitrary time could be infinite if an idle pCPU does not > receive an interrupt. So some part of domain resource will never be > freed. > > If I am power-cycling a domain in loop, after some time the > toolstack > will fail to allocate memory because of exhausted resources. > Previous > instance of the domain was not yet fully destroyed (e.g > complete_domain_destroy was not called). > Do you have a script and/or some more info for letting me try to reproduce it (e.g., you say some otf the vCPUs are pinned, which one? etc)? I'm a bit curious about why you're saying this is being exposed by using Credit2. In fact: 1) I've power-cycled quite a few domains in these last months, while under Credit2, and I don't think I have encountered it on x86; 2) I see how it may be related to Credit2 being more deterministic and not trying to schedule stuff around pseudo-randomly like Credit1 does... but I'd like to try investigating a bit more. Thanks and Regards, Dario -- <<This happens because I choose it to happen!>> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) Attachment:
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