Re: [Qemu-devel] VM stops responding, 100% CPU, switching to monitor fails

[Steve Fosdick <lists@pelvoux.nildram.co.uk>]

On Tue, 2009-02-03 at 09:11 -0800, Nathan wrote:
> Hi Steve,
> 
> This may be the issue I just posted about.  To test, in the host, run
> strace on the qemu process.
> 
> If the output shows many SIGALRM signals between fewer calls to
> "clone" which return ERESTARTNOINTR, then it's the same issue and I
> can advise you.
> 
> Otherwise, I'm not much help (I'm new to qemu).
> 
> regards,
> Nathan Wilcox

Interestingly if I attach to the qemu process with strace the guest VM
starts working again and continues to work after I have stopped the
strace command with control-C.

Here is a sample of what strace was giving:

--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0x63d24020)                = 0
select(16, [11 14 15], [], [], {0, 0})  = 0 (Timeout)
gettimeofday({1233684242, 162854}, NULL) = 0
clock_gettime(CLOCK_MONOTONIC, {87714, 363355675}) = 0
clock_gettime(CLOCK_MONOTONIC, {87714, 363373833}) = 0
clock_gettime(CLOCK_MONOTONIC, {87714, 363390595}) = 0
clock_gettime(CLOCK_MONOTONIC, {87714, 363406519}) = 0
clock_gettime(CLOCK_MONOTONIC, {87714, 363421884}) = 0
timer_gettime(0, {it_interval={0, 0}, it_value={0, 0}}) = 0
timer_settime(0, 0, {it_interval={0, 0}, it_value={0, 952000}}, NULL) =
0
ioctl(10, SPIOCSTYPE or VTXIOCGETINFO, 0x7fffba4f51d0) = 0
ioctl(10, SPIOCSTYPE or VTXIOCGETINFO, 0x7fffba4f51d0) = 0
ioctl(10, SPIOCSTYPE or VTXIOCGETINFO, 0x7fffba4f51d0) = 0
ioctl(10, SPIOCSTYPE or VTXIOCGETINFO, 0x7fffba4f51d0) = 0
ioctl(10, SPIOCSTYPE or VTXIOCGETINFO, 0x7fffba4f51d0) = 0

Regards,
Steve.