Re: [Xen-devel] null scheduler bug

[Milan Boberic <milanboberic94@xxxxxxxxx>]

Hey,
yes, I can see prink's outputs on console and in xl dmesg. Also added
timestamps, here are the results (created and destroyed domU a few
times, just to get more values), this is from xl dmesg:

NULL SCHEDULER - Not stressed PetaLinux host domain.

(XEN) t=218000327743:End of a domain_destroy function
(XEN) t=218000420874:End of a complete_domain_destroy function
(XEN) <G><3>memory_map:add: dom2 gfn=ff0a0 mfn=ff0a0 nr=1
(XEN) t=250216234232:End of a domain_destroy function
(XEN) t=250216326943:End of a complete_domain_destroy function
(XEN) <G><3>memory_map:add: dom3 gfn=ff0a0 mfn=ff0a0 nr=1
(XEN) t=842722811648:End of a domain_destroy function
(XEN) t=842722906089:End of a complete_domain_destroy function
(XEN) <G><3>memory_map:add: dom4 gfn=ff0a0 mfn=ff0a0 nr=1
(XEN) t=845884879948:End of a domain_destroy function
(XEN) t=845884972539:End of a complete_domain_destroy function
(XEN) <G><3>memory_map:add: dom5 gfn=ff0a0 mfn=ff0a0 nr=1
(XEN) t=847696699336:End of a domain_destroy function
(XEN) t=847696793097:End of a complete_domain_destroy function
(XEN) <G><3>memory_map:add: dom6 gfn=ff0a0 mfn=ff0a0 nr=1
(XEN) t=919260640576:End of a domain_destroy function
(XEN) t=919260732907:End of a complete_domain_destroy function

Stressed PetaLinux host with command: yes > /dev/null &

(XEN) t=3247747255872:End of a domain_destroy function
(XEN) t=3247747349863:End of a complete_domain_destroy function
(XEN) t=3253855263752:End of a domain_destroy function
(XEN) t=3253855357563:End of a complete_domain_destroy function
(XEN) <G><3>memory_map:add: dom10 gfn=ff0a0 mfn=ff0a0 nr=1
(XEN) t=3256797406444:End of a domain_destroy function
(XEN) t=3256797498584:End of a complete_domain_destroy function
(XEN) <G><3>memory_map:add: dom11 gfn=ff0a0 mfn=ff0a0 nr=1
(XEN) t=3259750219352:End of a domain_destroy function
(XEN) t=3259750313903:End of a complete_domain_destroy function
(XEN) <G><3>memory_map:add: dom12 gfn=ff0a0 mfn=ff0a0 nr=1
(XEN) t=3262418200662:End of a domain_destroy function
(XEN) t=3262418295912:End of a complete_domain_destroy function


CREDIT SCHEDULER - not stressed PetaLinux host

(XEN) t=86245669606:End of a domain_destroy function
(XEN) t=86245761127:End of a complete_domain_destroy function
(XEN) t=93862614736:End of a domain_destroy function
(XEN) t=93862702657:End of a complete_domain_destroy function
(XEN) t=96298736227:End of a domain_destroy function
(XEN) t=96298826618:End of a complete_domain_destroy function
(XEN) t=98042498304:End of a domain_destroy function
(XEN) t=98042590255:End of a complete_domain_destroy function
(XEN) t=99755209642:End of a domain_destroy function
(XEN) t=99755302643:End of a complete_domain_destroy function
(XEN) t=101441462434:End of a domain_destroy function
(XEN) t=101441553985:End of a complete_domain_destroy function

Stressed PetaLinux host with yes > /dev/null &

(XEN) t=331229997499:End of a domain_destroy function
(XEN) t=331230091770:End of a complete_domain_destroy function
(XEN) t=334493673726:End of a domain_destroy function
(XEN) t=334493765647:End of a complete_domain_destroy function
(XEN) t=336834521515:End of a domain_destroy function
(XEN) t=336834613326:End of a complete_domain_destroy function
(XEN) t=339215230042:End of a domain_destroy function
(XEN) t=339215321153:End of a complete_domain_destroy function

Also thank you for taking your time to help me, best regards!

On Thu, Sep 20, 2018 at 6:09 PM Dario Faggioli <dfaggioli@xxxxxxxx> wrote:
>
> Hey,
>
> Sorry for not having followed up. I was (and still am) planning to, but
> am also a bit busy.
>
> On Thu, 2018-09-20 at 15:04 +0200, Milan Boberic wrote:
> > I ran some more tests and managed to successfully create and destroy
> > domU as many times as I want, without any delay between destroy and
> > create.
> > I added:
> >  printk("End of a domain_destroy function");
> >  in domain_destroy function and
> > printk("End of a complete_domain_destroy function"); in
> > complete_domain_destroy function, at the end of the functions.
> > Those functions are in domain.c file.
> >
> Right. This is exactly the kind of debug patch I wanted to
> suggest/send. It is, in fact, what was being use to diagnose/fix the
> RCU issue, when it first came up, as you may have seen.
>
> > Now, after every xl create it prints:
> >
> > root@uz3eg-iocc-2018-2:~# xl create bm1.cfg
> > Parsing config from bm1.cfg
> > <G><3>memory_map:add: dom2 gfn=ff0a0 mfn=ff0a0 nr=1
> >
> Mmm... So, you added a printk() (or, actually, two of them) in the
> domain destruction path, and are seeing (different) things being
> printed during domain creation? How nice! :-D
>
> I'm not sure how that happens, and whether/how this new output relates
> to the problem. However, what about the printk() you added? Do you see
> their output? It may be visible only on the console and/or in `xl
> dmesg'.
>
> While there, if you can, I'd add timestamsp, e.g.:
>
> printk("t=%"PRI_stime":End of a domain_destroy function", NOW());
> printk("t=%"PRI_stime":End of a complete_domain_destroy function", NOW());
>
> and check what the outpur looks like both under credit or credit2, and
> under null.
>
> Regards,
> Dario
> --
> <<This happens because I choose it to happen!>> (Raistlin Majere)
> -----------------------------------------------------------------
> Dario Faggioli, Ph.D, http://about.me/dario.faggioli
> Software Engineer @ SUSE https://www.suse.com/

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