Re: [Xen-devel] kernel bootup slow issue on ovm3.1.1

["zhenzhong.duan" <zhenzhong.duan@xxxxxxxxxx>]

于 2012-08-08 00:26, Konrad Rzeszutek Wilk 写道:

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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