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[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

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** Changed in: linux (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1591504

Title:
  On function  __schedule issue.

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  On function __schedule have bottleneck efect.
  Bellow is perf report result:
  .............................
  -   12,61%    12,61%  gmain            [kernel.kallsyms]    [k] __schedule                                      ▒
       0x40f62674c0854803                                                                                         ▒
       __GI___libc_poll                                                                                           ▒
       entry_SYSCALL_64_fastpath                                                                                  ▒
       sys_poll                                                                                                   ▒
       do_sys_poll                                                                                                ▒
       poll_schedule_timeout                                                                                      ▒
       schedule_hrtimeout_range                                                                                   ▒
       schedule_hrtimeout_range_clock                                                                             ▒
       schedule                                                                                                   ▒
       __schedule  
  .......................................

    __schedule  /proc/kcore                                                                                          
         │     ↓ je     580
         │       mov    %gs:0x7e7e9750(%rip),%r14d
         │       movl   $0x1,%gs:0x7e7f5a8d(%rip)
         │       cmp    %r13,%r12
         │     ↓ je     755
         │       mov    %r12,%gs:0x7e7f5a74(%rip)
         │       mov    %r14d,%r14d
         │       lock   bts    %r14,0x2d0(%r12)
         │       mov    $0x80000000,%edi
         │       add    0x40(%r12),%rdi
         │       movabs $0x77ff80000000,%rax
         │       cmovb  0x5f059b(%rip),%rax        # 0xffffffff81e11010
         │       add    %rax,%rdi
         │       mov    %rdi,%cr3
         │       nop
         │       nop
         │2c4:   lock   btr %r14,0x2d0(%r13)
         │       nop
         │       mov    0x330(%r12),%eax
  100,00 │       test   %eax,%eax
         │     ↓ je     6d1
         │       mov    %gs:0x7e7f5a26(%rip),%rax
         │       mov    %rax,%rdi
         │       or     $0x100,%rdi
         │       cmp    %rdi,%rax
         │     ↓ je     308
  ..................

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: linux-image-4.4.0-22-generic 4.4.0-22.40
  ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
  Uname: Linux 4.4.0-22-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2.1
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/pcmC0D0p:   asu        3213 F...m pulseaudio
   /dev/snd/controlC0:  asu        3213 F.... pulseaudio
  CurrentDesktop: MATE
  Date: Sat Jun 11 15:29:36 2016
  InstallationDate: Installed on 2016-04-29 (42 days ago)
  InstallationMedia: Ubuntu-Studio 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
  IwConfig:
   lo        no wireless extensions.
   
   enp1s0    no wireless extensions.
  MachineType: Olidata S.p.A. ALABAMA
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.4.0-22-generic root=/dev/mapper/192--168--0--108--vg-root ro
  RelatedPackageVersions:
   linux-restricted-modules-4.4.0-22-generic N/A
   linux-backports-modules-4.4.0-22-generic  N/A
   linux-firmware                            1.157
  RfKill:
   
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 07/08/2008
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: S0101
  dmi.board.asset.tag: To Be Filled By O.E.M.
  dmi.board.name: To be filled by O.E.M.
  dmi.board.vendor: To be filled by O.E.M.
  dmi.board.version: To be filled by O.E.M.
  dmi.chassis.asset.tag: To Be Filled By O.E.M.
  dmi.chassis.type: 3
  dmi.chassis.vendor: To Be Filled By O.E.M.
  dmi.chassis.version: To Be Filled By O.E.M.
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrS0101:bd07/08/2008:svnOlidataS.p.A.:pnALABAMA:pvrToBeFilledByO.E.M.:rvnTobefilledbyO.E.M.:rnTobefilledbyO.E.M.:rvrTobefilledbyO.E.M.:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
  dmi.product.name: ALABAMA
  dmi.product.version: To Be Filled By O.E.M.
  dmi.sys.vendor: Olidata S.p.A.

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