Re: kernel bootup slow issue on ovm3.1.1

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

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? 2012-08-08 00:26, Konrad Rzeszutek Wilk ??:
> On Tue, Aug 07, 2012 at 03:22:50PM +0800, zhenzhong.duan wrote:
>> Hi maintainers,
>>
>> We meet a uek2 bootup slow issue on our ovm product(ovm3.0.3 and ovm3.1.1).
>>
>> The system env is an exalogic node with 24 cores + 100G mem (2 socket ,
>> 6 cores per socket, 2 HT threads per core).
>> After boot up this node with all cores enabled,
>> We boot a pvhvm with 12vpcus (or 24) + 90 GB + pci passthroughed device,
>> it takes 30+ mins to boot.
>> If we remove passthrough device from vm.cfg, bootup takes about 2 mins.
>> If we use a small mem(eg. 10G + 24 vcpus), bootup takes about 3 mins.
>> So a big mem + passthrough device made the worst case.
>>
>> If we boot this node with HT disabled from BIOS. Now only 12 cores are
>> available.
>> OVM on same node, same config with 12vpcus+90GB boots in 1.5 mins!
>>
>> After some debug, we found it's in kernel mtrr init that make this delay.
>>
>> mtrr_aps_init()
>>   \->  set_mtrr()
>>       \->  mtrr_work_handler()
>>
>> kernel spin in mtrr_work_handler.
>>
>> But we don't know the scene hide in the hypervisor. Why big mem +
>> passthrough made the worst case.
>> Is this already fixed in xen upstream?
>> Any comments are welcome, I'll upload all data depend on your need.
> What happens if you run with a upstream version of kernel? Say v3.4.7 ?
Hi konrad, Jan,

I tried 3.5.0-2.fc17.x86_64 and 3.6.0-rc1.
*
3.5.0-2.fc17.x86_64 took ~30 mins.*
Below is piece of fc17 dmesg:
  #22[    0.002999] installing Xen timer for CPU 22
  #23[    0.002999] installing Xen timer for CPU 23
[    1.844896] Brought up 24 CPUs
[    1.844898] Total of 24 processors activated (140449.34 BogoMIPS).
*block for 30 mins here.*
[    1.899794] devtmpfs: initialized
[    1.905956] atomic64 test passed for x86-64 platform with CX8 and 
with SSE
*
3.6.0-rc1 took more than 2 hours.*
piece of dmesg:
cpu 22 spinlock event irq 218
[    1.884775]  #22[    0.001999] installing Xen timer for CPU 22
cpu 23 spinlock event irq 225
[    1.932764]  #23[    0.001999] installing Xen timer for CPU 23
[    1.977734] Brought up 24 CPUs
[    1.978706] smpboot: Total of 24 processors activated (140449.34 
BogoMIPS)
*block for more than 2 hours here.*
[    1.988859] devtmpfs: initialized
[    2.021785] dummy:
[    2.023706] NET: Registered protocol family 16
[    2.026735] ACPI: bus type pci registered
[    2.028002] PCI: Using configuration type 1 for base access

I also send a patch to lkml that can workaround this issue, but I don't 
know the reason of block in xen side.
link: https://lkml.org/lkml/2012/8/7/50

regards
zduan

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