[Bug 1890069] [NEW] QEMU is not allowing multiple cores with mips architecture

[Skyler Mäntysaari]

Public bug reported:

I may have found a bug as when trying to boot up an QEMU VM with the
following command: "qemu-system-mips -M malta -m 512 -hda hda.img
-kernel vmlinux-4.19.0-10-4kc-malta -initrd initrd.img-4.19.0-10-4kc-
malta -append "root=/dev/sda1 console=ttyS0" -nographic -device
e1000,netdev=user.0 -netdev user,id=user.0,hostfwd=tcp::5555-:22 -smp
cores=12,threads=1,sockets=1", it will use up all of the CPU cores on
the host, but not bootup?

Kernel log also shows:
[  100.303136] perf: interrupt took too long (2506 > 2500), lowering 
kernel.perf_event_max_sample_rate to 79750
[  107.656869] perf: interrupt took too long (3195 > 3132), lowering 
kernel.perf_event_max_sample_rate to 62500
[  117.668390] perf: interrupt took too long (4033 > 3993), lowering 
kernel.perf_event_max_sample_rate to 49500
[  217.166763] perf: interrupt took too long (5126 > 5041), lowering 
kernel.perf_event_max_sample_rate to 39000
[  231.910132] perf: interrupt took too long (6445 > 6407), lowering 
kernel.perf_event_max_sample_rate to 31000
[  250.170677] perf: interrupt took too long (8087 > 8056), lowering 
kernel.perf_event_max_sample_rate to 24500
[  285.391451] perf: interrupt took too long (10126 > 10108), lowering 
kernel.perf_event_max_sample_rate to 19750
[  778.588911] perf: interrupt took too long (12770 > 12657), lowering 
kernel.perf_event_max_sample_rate to 15500
[ 1554.825129] perf: interrupt took too long (15982 > 15962), lowering 
kernel.perf_event_max_sample_rate to 12500
[ 1622.838910] hrtimer: interrupt took 14758063 ns
[ 1712.932777] INFO: NMI handler (perf_event_nmi_handler) took too long to run: 
0.000 msecs
[ 1712.932780] perf: interrupt took too long (59793 > 19977), lowering 
kernel.perf_event_max_sample_rate to 3250


System details:

OS: Ubuntu 20.04
QEMU emulator version 4.2.0 (Debian 1:4.2-3ubuntu6.3)

** Affects: qemu (Ubuntu)
     Importance: Undecided
         Status: New

** Project changed: launchpad => qemu

** Project changed: qemu => qemu (Ubuntu)

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https://bugs.launchpad.net/bugs/1890069

Title:
  QEMU is not allowing multiple cores with mips architecture

Status in qemu package in Ubuntu:
  New

Bug description:
  I may have found a bug as when trying to boot up an QEMU VM with the
  following command: "qemu-system-mips -M malta -m 512 -hda hda.img
  -kernel vmlinux-4.19.0-10-4kc-malta -initrd initrd.img-4.19.0-10-4kc-
  malta -append "root=/dev/sda1 console=ttyS0" -nographic -device
  e1000,netdev=user.0 -netdev user,id=user.0,hostfwd=tcp::5555-:22 -smp
  cores=12,threads=1,sockets=1", it will use up all of the CPU cores on
  the host, but not bootup?

  Kernel log also shows:
  [  100.303136] perf: interrupt took too long (2506 > 2500), lowering 
kernel.perf_event_max_sample_rate to 79750
  [  107.656869] perf: interrupt took too long (3195 > 3132), lowering 
kernel.perf_event_max_sample_rate to 62500
  [  117.668390] perf: interrupt took too long (4033 > 3993), lowering 
kernel.perf_event_max_sample_rate to 49500
  [  217.166763] perf: interrupt took too long (5126 > 5041), lowering 
kernel.perf_event_max_sample_rate to 39000
  [  231.910132] perf: interrupt took too long (6445 > 6407), lowering 
kernel.perf_event_max_sample_rate to 31000
  [  250.170677] perf: interrupt took too long (8087 > 8056), lowering 
kernel.perf_event_max_sample_rate to 24500
  [  285.391451] perf: interrupt took too long (10126 > 10108), lowering 
kernel.perf_event_max_sample_rate to 19750
  [  778.588911] perf: interrupt took too long (12770 > 12657), lowering 
kernel.perf_event_max_sample_rate to 15500
  [ 1554.825129] perf: interrupt took too long (15982 > 15962), lowering 
kernel.perf_event_max_sample_rate to 12500
  [ 1622.838910] hrtimer: interrupt took 14758063 ns
  [ 1712.932777] INFO: NMI handler (perf_event_nmi_handler) took too long to 
run: 0.000 msecs
  [ 1712.932780] perf: interrupt took too long (59793 > 19977), lowering 
kernel.perf_event_max_sample_rate to 3250

  
  System details:

  OS: Ubuntu 20.04
  QEMU emulator version 4.2.0 (Debian 1:4.2-3ubuntu6.3)

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