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Re: [Xen-devel] Introduce rtds real-time scheduler for Xen

Hi Dario,

First, thank you so much for testing it. I really appreciate it. :-)

2014-09-17 10:15 GMT-04:00 Dario Faggioli <dario.faggioli@xxxxxxxxxx>:
On dom, 2014-09-14 at 17:37 -0400, Meng Xu wrote:
> This serie of patches adds rtds real-time scheduler to Xen.
>
I gave this series some testing, and the behavior of the scheduler is as
expected, so again, Meng and Sisu, good work.

While doing it, I've also put the series in this git repo/branch:

 git://xenbits.xen.org/people/dariof/xen.git sched/rt/rtds-v3
 http://xenbits.xen.org/gitweb/?p=people/dariof/xen.git;a=shortlog;h=refs/heads/sched/rt/rtds-v3


There are a couple of issue, though, one minor and one serious, which
I'd like you to fix, if possible, before freeze date. More info below.

> //list VCPUs' parameters of each domain in cpu pools using rtds scheduler
> #xl sched-rtds
> Cpupool Pool-0: sched=EDF
> Name                ID  Period  Budget
> Domain-0Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â0Â Â Â10000Â Â Â 4000
> vm1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 1Â Â Â10000Â Â Â 4000
>
So, when I boot Xen with sched=rtds, issueing this command (`xl
sched-rtds') produces a lot of printk on the serial console, basically
outputting the dump of the scheduler information.

I guess there is one call to rt_sched_dump() (or whatever that was) left
somewhere. Could you please check?

This is not a serious issue, but since you're resending anyway...

> //create a cpupool test
> #xl cpupool-cpu-remove Pool-0 3
> #xl cpupool-cpu-remove Pool-0 2
> #xl cpupool-create name=\"test\" sched=\"rtds\"
> #xl cpupool-cpu-add test 3
> #xl cpupool-cpu-add test 2
> #xl cpupool-list
> Name       ÂCPUs ÂSched  ÂActive ÂDomain count
> Pool-0       Â2  Ârtds   Ây     2
> test        Â2  Ârtds   Ây     0
>
This works for me too.

Booting with sched=credit, creating an rtds cpupool and migruting
domains there also works here too.

However, booting with sched=rtds, and issuing the following commands:
# xl cpupool-cpu-remove Pool-0 20
# xl cpupool-cpu-remove Pool-0 21
# xl cpupool-create /etc/xen/be-cpupool

Where /etc/xen/be-cpupool looks like this:
Âname = "be"
Âsched = "credit"
Âcpus = ["20", "21"]
Âsched="credit"

Makes Xen *CRASH* with the following trace:

(XEN) ----[ Xen-4.5-unstable x86_64 debug=y Not tainted ]----
(XEN) ----[ Xen-4.5-unstable x86_64 debug=y Not tainted ]----
(XEN) CPU:Â Â 20
(XEN) CPU:Â Â 21
(XEN) RIP:Â Â e008:[<ffff82d08012bb1e>]RIP:Â Â e008:[<ffff82d08012bb1e>] check_lock+0x1e/0x3b check_lock+0x1e/0x3b
(XEN) RFLAGS: 0000000000010002
(XEN) RFLAGS: 0000000000010002Â ÂCONTEXT: hypervisor
(XEN) CONTEXT: hypervisor
(XEN) rax: 0000000000000001Â Ârbx: 0000000000000000Â Ârcx: 0000000000000001
(XEN) rax: 0000000000000001Â Ârbx: 0000000000000000Â Ârcx: 0000000000000001
(XEN) rdx: 0000000000000001Â Ârsi: ffff830917fc4c80Â Ârdi: 0000000000000004
(XEN) rdx: 0000000000000001Â Ârsi: ffff830917fc2c80Â Ârdi: 0000000000000004
(XEN) rbp: ffff830917fb7e08Â Ârsp: ffff830917fb7e08Â Âr8:Â 0000001d52034e80
(XEN) rbp: ffff830917fafe08Â Ârsp: ffff830917fafe08Â Âr8:Â 0000000000000000
(XEN) r9: ffff830828a47978 Âr10: 00000000deadbeef Âr11: 0000000000000246
(XEN) r9: ffff830917fe3ea8 Âr10: 00000000deadbeef Âr11: 0000000000000246
(XEN) r12: 0000001d51efbd89Â Âr13: ffff82d080320de0Â Âr14: 0000000000000000
(XEN) r12: 0000001d51efbb99Â Âr13: ffff82d080320de0Â Âr14: 0000000000000000
(XEN) r15: 0000000000000014 Âcr0: 000000008005003b Âcr4: 00000000000026f0
(XEN) r15: 0000000000000015 Âcr0: 000000008005003b Âcr4: 00000000000026f0
(XEN) cr3: 00000000cf08f000Â Âcr2: 0000000000000004
(XEN) cr3: 00000000cf08f000Â Âcr2: 0000000000000004
(XEN) ds: 002b Âes: 002b Âfs: 0000 Âgs: 0000 Âss: e010 Âcs: e008
(XEN) ds: 002b Âes: 002b Âfs: 0000 Âgs: 0000 Âss: e010 Âcs: e008
(XEN) Xen stack trace from rsp=ffff830917fb7e08:
(XEN)Â ÂXen stack trace from rsp=ffff830917fafe08:
(XEN)Â Â ffff830917fb7e20 ffff830917fafe20 ffff82d08012bbc4 ffff82d08012bbc4 ffff8300cf12d000 ffff8300cf12c000 ffff830917fb7eb0 ffff830917fafeb0
(XEN)
(XEN)Â Â ffff82d080128175 ffff82d080128175 ffff830917fb7e40 ffff830917fafe40 ffff82d0801879ef ffff82d0801879ef 0000001400fb7e60 0000001500fafe60
(XEN)
(XEN)Â Â ffff830917fc4060 ffff830917fc2060 ffff830917fb7e60 ffff830917fafe60 ffff830917fc4200 ffff830917fc2200 ffff830917fb7eb0 ffff830917fafeb0
(XEN)
(XEN)Â Â ffff82d08012e983 ffff82d08012e983 ffff830917fb7ef0 ffff830917fafef0 ffff82d0801aa941 ffff82d0801aa941 ffff830917fb7e90 ffff830917fafe90
(XEN)
(XEN)Â Â ffff82d0802f8980 ffff82d0802f8a00 ffff82d0802f7f80 ffff82d0802f7f80 ffffffffffffffff ffffffffffffffff ffff830917fb0000 ffff830917fa8000
(XEN)
(XEN)Â Â 00000000000f4240 00000000000f4240 ffff830917fb7ee0 ffff830917fafee0 ffff82d08012b539 ffff82d08012b539 ffff830917fb0000 ffff830917fa8000
(XEN)
(XEN)Â Â 0000001d51dfd294 0000001d51dfcb8f ffff8300cf12d000 ffff8300cf12c000 ffff83092d6a0990 ffff83092d6a0990 ffff830917fb7ef0 ffff830917fafef0
(XEN)
(XEN)Â Â ffff82d08012b591 ffff82d08012b591 ffff830917fb7f10 ffff830917faff10 ffff82d080160425 ffff82d080160425 ffff82d08012b591 ffff82d08012b591
(XEN)
(XEN)Â Â ffff8300cf12d000 ffff8300cf12c000 ffff830917fb7e10 ffff830917fafe10 0000000000000000 0000000000000000 ffff88003a0cbfd8 ffff88003a0edfd8
(XEN)
(XEN)Â Â ffff88003a0cbfd8 ffff88003a0edfd8 0000000000000007 0000000000000014 ffff88003a0cbec0 ffff88003a0edec0 0000000000000000 0000000000000000
(XEN)
(XEN)Â Â 0000000000000246 0000000000000246 0000001c6462ff88 0000001c986bebc8 0000000000000000 0000000000000000 0000000000000000 0000000000000000
(XEN)
(XEN)Â Â 0000000000000000 0000000000000000 ffffffff810013aa ffffffff810013aa ffffffff81c31160 ffffffff81c31160 00000000deadbeef 00000000deadbeef
(XEN)
(XEN)Â Â 00000000deadbeef 00000000deadbeef 0000010000000000 0000010000000000 ffffffff810013aa ffffffff810013aa 000000000000e033 000000000000e033
(XEN)
(XEN)Â Â 0000000000000246 0000000000000246 ffff88003a0cbea8 ffff88003a0edea8 000000000000e02b 000000000000e02b c2c2c2c2c2c2c2c2 c2c2c2c2c2c2c2c2
(XEN)
(XEN)Â Â c2c2c2c2c2c2c2c2 c2c2c2c2c2c2c2c2 c2c2c2c2c2c2c2c2 c2c2c2c2c2c2c2c2 c2c2c2c2c2c2c2c2 c2c2c2c2c2c2c2c2 c2c2c2c200000014 c2c2c2c200000015
(XEN)
(XEN)Â Â ffff8300cf12d000 ffff8300cf12c000 0000003897ca3280 0000003897ca1280 c2c2c2c2c2c2c2c2 c2c2c2c2c2c2c2c2
(XEN)
(XEN) Xen call trace:
(XEN) Xen call trace:
(XEN)Â Â [<ffff82d08012bb1e>] check_lock+0x1e/0x3b
(XEN)Â Â [<ffff82d08012bb1e>] check_lock+0x1e/0x3b
(XEN)Â Â [<ffff82d08012bbc4>] _spin_lock_irq+0x1b/0x6c
(XEN)Â Â [<ffff82d08012bbc4>] _spin_lock_irq+0x1b/0x6c
(XEN)Â Â [<ffff82d080128175>] schedule+0xc0/0x5da
(XEN)Â Â [<ffff82d080128175>] schedule+0xc0/0x5da
(XEN)Â Â [<ffff82d08012b539>] __do_softirq+0x81/0x8c
(XEN)Â Â [<ffff82d08012b539>] __do_softirq+0x81/0x8c
(XEN)Â Â [<ffff82d08012b591>] do_softirq+0x13/0x15
(XEN)Â Â [<ffff82d08012b591>] do_softirq+0x13/0x15
(XEN)Â Â [<ffff82d080160425>] idle_loop+0x5e/0x6e
(XEN)Â Â [<ffff82d080160425>] idle_loop+0x5e/0x6e
(XEN)
(XEN)
(XEN) Pagetable walk from 0000000000000004:
(XEN) Pagetable walk from 0000000000000004:
(XEN)Â L4[0x000] = 000000092d6a4063 ffffffffffffffff
(XEN)Â L4[0x000] = 000000092d6a4063 ffffffffffffffff
(XEN)Â L3[0x000] = 000000092d6a3063 ffffffffffffffff
(XEN)Â L3[0x000] = 000000092d6a3063 ffffffffffffffff
(XEN)Â L2[0x000] = 000000092d6a2063 ffffffffffffffff
(XEN)Â L2[0x000] = 000000092d6a2063 ffffffffffffffff
(XEN)Â L1[0x000] = 0000000000000000 ffffffffffffffff
(XEN)Â L1[0x000] = 0000000000000000 ffffffffffffffff
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 20:
(XEN) FATAL PAGE FAULT
(XEN) [error_code=0000]
(XEN) Faulting linear address: 0000000000000004
(XEN) ****************************************
(XEN)
(XEN) Manual reset required ('noreboot' specified)
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 21:
(XEN) FATAL PAGE FAULT
(XEN) [error_code=0000]
(XEN) Faulting linear address: 0000000000000004
(XEN) ****************************************
(XEN)
(XEN) Manual reset required ('noreboot' specified)

Can you please check, try to reproduce, and fix ASAP?

âSure! Start doing it now. I will try to reproduce it and let you know.â
Â

This, IMO, does not alter the prognosis, wrt 4.5 inclusion, at least not
per-se. In fact, it's ok for some bugs to be around at feature freeze
time, for the features we said we want. What we need to know is that
we're likely going to be able to fix them without making the release
slip.

So you should really either fix this, or provide here enough insights,
to convince people you're on the way to that. :-)

âSure! Thanks!

Mengâ
Â

Â

--


-----------
Meng Xu
PhD Student in Computer and Information Science
University of Pennsylvania
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