← Back to team overview

kernel-packages team mailing list archive

[Bug 1531768] Re: arm64 kernel and multiple CPUs is unusably slow


I take that back. It does survive for much longer, but after some 15
minutes of running I again run into tons of

[ 2424.611668] INFO: task systemd-udevd:1320 blocked for more than 120 seconds.
[ 2424.613514]       Tainted: G        W       4.2.0-22-generic #27-Ubuntu
[ 2424.615183] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2424.617166] systemd-udevd   D ffffffc000086ee4     0  1320      1 0x0000000c
[ 2424.617176] Call trace:
[ 2424.617842] [<ffffffc000086ee4>] __switch_to+0x94/0xa8
[ 2424.617851] [<ffffffc0008a7100>] __schedule+0x2b0/0x7b8
[ 2424.617854] [<ffffffc0008a7644>] schedule+0x3c/0x98
[ 2424.617859] [<ffffffc0008aa954>] schedule_timeout+0x1ec/0x280
[ 2424.617862] [<ffffffc0008a8364>] wait_for_common+0xcc/0x1a0
[ 2424.617866] [<ffffffc0008a8460>] wait_for_completion+0x28/0x38
[ 2424.617870] [<ffffffc000120654>] __synchronize_srcu+0x9c/0x180
[ 2424.617873] [<ffffffc000120770>] synchronize_srcu+0x38/0x48
[ 2424.617877] [<ffffffc00028b7b4>] fsnotify_destroy_group+0x2c/0x60
[ 2424.617880] [<ffffffc00028de3c>] inotify_release+0x34/0x78
[ 2424.617885] [<ffffffc00024537c>] __fput+0xa4/0x248
[ 2424.617887] [<ffffffc000245598>] ____fput+0x20/0x30
[ 2424.617892] [<ffffffc0000e0604>] task_work_run+0xbc/0xf8
[ 2424.617896] [<ffffffc0000c29d0>] do_exit+0x2f0/0xa48
[ 2424.617898] [<ffffffc0000c31bc>] do_group_exit+0x44/0xe8
[ 2424.617902] [<ffffffc0000d09b8>] get_signal+0x3d8/0x578
[ 2424.617906] [<ffffffc000089f20>] do_signal+0x90/0x530
[ 2424.617909] [<ffffffc00008a640>] do_notify_resume+0x70/0x78

for all kinds of processes.

** Summary changed:

- arm64 kernel and >= 8 CPUS (>= host CPU count?) is unusably slow with lxd operations
+ arm64 kernel and multiple CPUs is unusably slow

You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.

  arm64 kernel and multiple CPUs is unusably slow

Status in linux package in Ubuntu:

Bug description:
  I created an 8 CPU arm64 instance on Canonical's Scalingstack (which I
  want to use for armhf autopkgtesting in LXD). I started with wily as
  that has lxd available (it's not yet available in trusty nor the PPA
  for arm64).

  However, pretty much any LXD task that I do (I haven't tried much
  else) on this machine takes unbearably long. A simple "lxc profile set
  default raw.lxc lxc.seccomp=" or "lxc list" takes several minutes.

  I see tons of

  [ 1020.971955] rcu_sched kthread starved for 6000 jiffies! g1095 c1094 f0x0
  [ 1121.166926] INFO: task fsnotify_mark:69 blocked for more than 120 seconds.

  in dmesg (the attached apport info has the complete dmesg).

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: linux-image-4.2.0-22-generic 4.2.0-22.27
  ProcVersionSignature: User Name 4.2.0-22.27-generic 4.2.6
  Uname: Linux 4.2.0-22-generic aarch64
   total 0
   crw-rw---- 1 root audio 116,  1 Jan  7 09:18 seq
   crw-rw---- 1 root audio 116, 33 Jan  7 09:18 timer
  AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
  ApportVersion: 2.19.1-0ubuntu5
  Architecture: arm64
  ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
  AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
  Date: Thu Jan  7 09:24:01 2016
   eth0      no wireless extensions.

   lo        no wireless extensions.

   lxcbr0    no wireless extensions.
   00:00.0 Host bridge [0600]: Red Hat, Inc. Device [1b36:0008]
    Subsystem: Red Hat, Inc Device [1af4:1100]
    Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
    Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
  Lsusb: Error: command ['lsusb'] failed with exit code 1: unable to initialize libusb: -99

   PATH=(custom, no user)

  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-22-generic root=LABEL=cloudimg-rootfs earlyprintk
   linux-restricted-modules-4.2.0-22-generic N/A
   linux-backports-modules-4.2.0-22-generic  N/A
   linux-firmware                            1.149.3
  RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
  SourcePackage: linux
  UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
  UpgradeStatus: No upgrade log present (probably fresh install)

To manage notifications about this bug go to: