Re: kernel bootup slow issue on ovm3.1.1

["zhenzhong.duan" <zhenzhong.duan@oracle.com>]

于 2012-08-08 23:01, Jan Beulich 写道:
>>>> On 08.08.12 at 11:48, "zhenzhong.duan"<zhenzhong.duan@oracle.com>  wrote:
>> 于 2012-08-07 16:37, Jan Beulich 写道:
>>>>>> On 07.08.12 at 09:22, "zhenzhong.duan"<zhenzhong.duan@oracle.com>   wrote:
>>> Next, if you already spotted where the spinning occurs, you
>>> should also be able to tell what's going on at the other side, i.e.
>>> why the event that is being waited for isn't occurring for this
>>> long a time. Since there's a number of open coded spin loops
>>> here, knowing exactly which one each CPU is sitting in (and
>>> which ones might not be in any) is the fundamental information
>>> needed.
>>>
>>>   From what you're telling us so far, I'd rather suspect a kernel
>>> problem, not a hypervisor one here.
>> Per my finding, most of vcpus spin at set_atomicity_lock.
> Then you need to determine what the current owner of the
> lock is doing.
I add printk.time=1 to kernel cmdline, but dmesg don't show much help.

[    1.978706] smpboot: Total of 24 processors activated (140449.34 
BogoMIPS)
(block ~30 mins)
[    1.988859] devtmpfs: initialized
>
>> Some spin at stop_machine after finish their job.
> And here you'd need to find out what they're waiting for,
> and what those CPUs are doing.
They are waiting the vcpu calling generic_set_all and those spin at 
set_atomicity_lock.
In fact, all are waiting generic_set_all
>
>> Only one vcpu is calling generic_set_all.
>> I'm not sure if the vcpu calling generic_set_all don't have higher
>> priority and maybe preempt by other vcpus and dom0 frequently.
>> This waste much time.
> There's not that much being done in generic_set_all(), so the
> code should finish reasonably quickly. Are you perhaps having
> more vCPU-s in the guest than pCPU-s they can run on?
System env is an exalogic node with 24 cores + 100G mem (2 socket , 6 
cores per socket, 2 HT threads per core).
Bootup a pvhvm with 12vpcus (or 24) + 90 GB + pci passthroughed device.
>   Does
> your hardware support Pause-Loop-Exiting (or the AMD
> equivalent, don't recall their term right now)?
I have no access to serial line, could I get the info by a command?
/proc/cpuinfo shows below:
cpu family      : 6
model           : 44
model name      : Intel(R) Xeon(R) CPU           X5670  @ 2.93GHz
>
> Jan

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