Comment 0 for bug 1547231

/proc/$pid/maps experienced a significant performance regression for processes with large numbers of threads between Precise and Trusty due to an upstream bug. This behavior is currently blocking my ability to upgrade to Trusty, as we depend on applications with with 10s of thousands of threads.

The issue has been fixed in the usptream -mm tree.

Upstream report: http://comments.gmane.org/gmane.linux.kernel.mm/144712
Upstream patches:
https://git.kernel.org/cgit/linux/kernel/git/mhocko/mm.git/commit/?h=since-4.4&id=2d2a106c79f4b5b2b10e72957f7448e276dbf0a9
https://git.kernel.org/cgit/linux/kernel/git/mhocko/mm.git/commit/?h=since-4.4&id=eb1899e03405faf7c79396ae9593303d53e2710d

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-36-generic 3.13.0-36.63
ProcVersionSignature: Ubuntu 3.13.0-36.63-generic 3.13.11.6
Uname: Linux 3.13.0-36-generic x86_64
AlsaDevices:
 total 0
 crw-rw---- 1 root audio 116, 1 Feb 18 12:13 seq
 crw-rw---- 1 root audio 116, 33 Feb 18 12:13 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
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 Feb 18 13:44:23 2016
MachineType: Supermicro A1SAi
PciMultimedia:

ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 astdrmfb
ProcKernelCmdLine: root=/dev/md1 ro console=tty0 console=ttyS0,57600
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-36-generic N/A
 linux-backports-modules-3.13.0-36-generic N/A
 linux-firmware 1.127.20
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux
UpgradeStatus: Upgraded to trusty on 2014-07-18 (579 days ago)
WifiSyslog:

dmi.bios.date: 02/27/2014
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1.0c
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: A1SAi
dmi.board.vendor: Supermicro
dmi.board.version: 123456789
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 18
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1.0c:bd02/27/2014:svnSupermicro:pnA1SAi:pvr123456789:rvnSupermicro:rnA1SAi:rvr123456789:cvnToBeFilledByO.E.M.:ct18:cvrToBeFilledByO.E.M.:
dmi.product.name: A1SAi
dmi.product.version: 123456789
dmi.sys.vendor: Supermicro