Re: [Qemu-devel] Migration issue with 4.0.x

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Andrey Korolyov (andrey@xdel.ru) wrote:
> Hello,
> 
> during tests against 4.0.5/4.0.6 for the problem described in
> https://lists.gnu.org/archive/html/qemu-devel/2015-06/msg03117.html I
> had noticed another weird issue: VM hangs after a couple of minutes
> after being migrated if the hypervisor is running mentioned kernel
> version. It does not matter for workload type during migration (idle
> VM hangs too) or memory configuration of the VM - I can type
> characters in the shell but dmesg listing takes about a minute to be
> displayed (as well as other I/O operations lilke ls). The main visible
> symptom is that I`ve not able to launch 'top' just after migration -
> it 'hangs' after reading its own pid stats:

Radim fixed a bug that was causing me a post migration hang, I'm not
sure if it's the same case though, worth trying the patch here:

http://article.gmane.org/gmane.comp.emulators.kvm.devel/136607

Dave

> 
>      0.000058 read(4, "2436 (bash) S 2434 2436 2436 34817 2514 4202752
> 4321 9165 0 3 0 13 0 6 20 0 1 0 55138 20561920 1045
> 18446744073709551615 4194304 5130324 140723572820800 140723572819456
> 139788860395630 0 65536 3686404 1266761467 0 0 0 17 0 0 0 0 0 0
> 7228872 7264912 17436672 140723572821400 140723572821406
> 140723572821406 140723572821998 0\n", 4095) = 324
>      0.000096 close(4)                  = 0
>      0.000061 open("/proc/2436/statm", O_RDONLY) = 4
>      0.000061 read(4, "5020 1045 755 229 0 293 0\n", 4095) = 26
>      0.000052 close(4)                  = 0
>      0.000053 brk(0x15da000)            = 0x15da000
>      0.000074 stat("/proc/2514", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0
>      0.000083 open("/proc/2514/stat", O_RDONLY) = 4
>      0.000065 read(4, "2514 (strace) S 2436 2514 2436 34817 2514
> 4202496 107 0 0 0 0 0 0 0 20 0 1 0 64452 4546560 124
> 18446744073709551615 4194304 4502860 140732305872800 140732305872152
> 139895671099674 0 0 3166215 0 0 0 0 17 4 0 0 0 0 0 6600016 6601324
> 9408512 140732305878369 140732305878401 140732305878401
> 140732305879016 0\n", 4095) = 305
>      0.000094 close(4)                  = 0
>      0.000062 open("/proc/2514/statm", O_RDONLY) = 4
>      0.000067 read(4, "1110 124 106 76 0 97 0\n", 4095) = 23
>      0.000051 close(4)                  = 0
>      0.000056 stat("/proc/2515", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0
>      0.000079 open("/proc/2515/stat", O_RDONLY) = 4
>      0.000056 read(4, "2515 (top) R 2514 2514 2436 34817 2514 4202496
> 206 0 0 0 0 0 0 0 20 0 1 0 64452 23875584 698 18446744073709551615
> 4194304 4257604 140736479316592 140736479312856 140491962546544 0 0 0
> 2147221247 0 0 0 17 4 0 0 0 0 0 6356400 6361288 22503424
> 140736479321472 140736479321476 140736479321476 140736479322091 0\n",
> 4095) = 307
>      0.000125 close(4)                  = 0
>      0.000063 open("/proc/2515/statm", O_RDONLY) = 4
>      0.000067 read(4, "5829 698 582 16 0 246 0\n", 4095) = 24
>      0.000052 close(4)                  = 0
>      0.000055 getdents(3, /* 0 entries */, 32768) = 0
>      0.000056 close(3)                  = 0
>      0.000055 nanosleep({0, 150000000}, NULL) = ?
> ERESTART_RESTARTBLOCK (To be restarted)
>     10.943440 --- SIGINT (Interrupt) @ 0 (0) ---
> 
> 
> 
> Please consider this to be a bug report, hosts are running 4.0.5, qemu
> is a tagged 2.3.0 and the guest is debian jessie 3.16. Unfortunately I
> do not have much time to bisect this one or go a bit more deeply right
> now, hopefully it would be possible on a weekend with enough spare
> time. Thanks!
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK