Re: [Xen-users] vCPUs are in 'b' (blocked) state: How to debug?

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, May 02, 2014 at 03:43:25PM -0700, Saurabh Mishra wrote:
> Hi,
> 
> 
> We saw CPU stalls in the VM and noticed 3/4 vCPUs are in blocked state. How
> can we debug this kind of problem? What can we capture through xl debug-key
> command or any other command?
> 

"blocked" means VCPU is waiting for event. There's nothing wrong with
this state by itself.

> 
> xl vpcu-list showed that three vCPUs out of 4 are in blocked state. We are
> using 'Xen 4.2.4_02-0.7.1'.
> 
> 
> ssc-lc-6:/var/log # tail pvm_console.log
> 
> [  264.177093] hongkong 0000:00:0b.0: FPGA version 0.7 card type 4 version
> 0.1 slot 5 (15) status 0x6536
> 
> [  264.186579] hongkong 0000:00:0b.0: HD downloaded by EFI, bypass Hongkong
> driver download procedure.
> 
> [  264.194566] hongkong 0000:00:0b.0: registering i2c-hk-0
> 
> [  264.199557] hongkong 0000:00:0b.0: registering i2c-hk-1
> 
> [  264.204027] hongkong 0000:00:0b.0: registering i2c-hk-2
> 
> [  264.208243] hongkong 0000:00:0b.0: registering i2c-hk-3
> 
> [  264.213244] SSC NVRAM: addr=0xf2100000 size=0x100000 flags=0x40200
> 
> [  264.242258] se-klognv: unable to open rtc device (rtc0)
> 
> [  264.342638] input: ImExPS/2 Generic Explorer Mouse as
> /devices/platform/i8042/serio1/input/input1
> 
> *[  324.244724] INFO: rcu_sched_state detected stalls on CPUs/tasks: { 3}
> (detected by 0, t=60002 jiffies)*
> 
> 

It's more likely a kernel issue. Dumping Xen (hypervisor) state won't
help you much. I don't know the kernel you use. If it is old, probably
you can check more recent version of kernel and see if it works?

Wei.


> 
> ssc-lc-6:/var/log # xl list
> 
> 
> Name                                        ID   Mem VCPUs   State
> Time(s)
> 
> Domain-0                                     0  8151     4     r-----
> 229.5
> 
> pvm-01-6                                     1  8187     4     r-----
> 244.1
> 
> 
> 
> xentop - 21:43:07   Xen 4.2.4_02-0.7.1
> 
> 2 domains: 2 running, 0 blocked, 0 paused, 0 crashed, 0 dying, 0 shutdown
> 
> Mem: 67095560k total, 17930632k used, 49164928k free    CPUs: 40 @ 2200MHz
> 
>       NAME  STATE   CPU(sec) CPU(%)     MEM(k) MEM(%)  MAXMEM(k) MAXMEM(%)
> VCPUS
> 
> NETS NETTX(k) NETRX(k) VBDS   VBD_OO   VBD_RD   VBD_WR  VBD_RSECT
> VBD_WSECT SS
> 
> ID
> 
>   Domain-0 -----r        246   54.4    8346880   12.4   no limit
> n/a     4
> 
>     0        0        0    0        0        0        0          0
> 0
> 
> 0
> 
>   pvm-01-6 -----r        337  104.2    8384476   12.5    8389632
> 12.5     4
> 
>     4      654        0    1        0        0        0          0
> 0

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