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Message #183527
[Bug 1591491] [NEW] On function __update_load_avg issue.
Public bug reported:
On this bug need litle explications function embedded
__compute_runnable_contrib have at beggining on "big" noop by 100 cycles
but why?
Looking bellow on contrib is added value but is not used for twice.
2715 /* Efficiently calculate \sum (1..n_period) 1024*y^i */
2716 contrib = __compute_runnable_contrib(periods);
2717 contrib = cap_scale(contrib, scale_freq);
2718 if (weight) {
Look here :
http://lxr.free-electrons.com/source/kernel/sched/fair.c#L2716
And content of perf :
__compute_runnable_contrib /proc/kcore
│
│
│
│ Disassembly of section load0:
│
│ ffffffff810b2c70 <load0>:
100,00 │ nop
│ cmp $0x20,%rdi
│ ↓ ja 13
│ mov -0x7e5e84c0(,%rdi,4),%eax
│ ← retq
│13: cmp $0x158,%rdi
│ ↓ ja 27
│ push %rbp
│ mov %rsp,%rbp
│ callq 0xffffffff810b2c10
│ pop %rbp
│ ← retq
│27: mov $0xba7e,%eax
│ ← retq
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 14:17:27 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.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: Confirmed
** Tags: amd64 apport-bug xenial
--
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1591491
Title:
On function __update_load_avg issue.
Status in linux package in Ubuntu:
Confirmed
Bug description:
On this bug need litle explications function embedded
__compute_runnable_contrib have at beggining on "big" noop by 100
cycles but why?
Looking bellow on contrib is added value but is not used for twice.
2715 /* Efficiently calculate \sum (1..n_period) 1024*y^i */
2716 contrib = __compute_runnable_contrib(periods);
2717 contrib = cap_scale(contrib, scale_freq);
2718 if (weight) {
Look here :
http://lxr.free-electrons.com/source/kernel/sched/fair.c#L2716
And content of perf :
__compute_runnable_contrib /proc/kcore
│
│
│
│ Disassembly of section load0:
│
│ ffffffff810b2c70 <load0>:
100,00 │ nop
│ cmp $0x20,%rdi
│ ↓ ja 13
│ mov -0x7e5e84c0(,%rdi,4),%eax
│ ← retq
│13: cmp $0x158,%rdi
│ ↓ ja 27
│ push %rbp
│ mov %rsp,%rbp
│ callq 0xffffffff810b2c10
│ pop %rbp
│ ← retq
│27: mov $0xba7e,%eax
│ ← retq
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 14:17:27 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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