touch-packages team mailing list archive

[Ruslan <b7.10110111@xxxxxxxxx>]

It appears to be the kernel bug. Sort of. I've bisected the kernel to commit ab8fabd46f811d5153d8a0cd2fac9a0d41fb593d. There's a discussion of this problem in this thread:
https://groups.google.com/forum/#!topic/linux.kernel/Jc69VRli3k0

This seems basically WONTFIX from linux side. But a workarounds are:

1. "vm.highmem_is_dirtyable=1" sysctl option — although this makes the performance not as high as it was in 3.2.x kernels, it at least allows one to use the disk subsystem
2. "mem=15G" kernel parameter limits the amount of usable memory, preventing the problems discussed in the thread I linked above
3. Use 64 bit kernel. This seems to be not a trivial thing to do with Ubuntu, but I may be wrong. But this is proposed as _the solution_.

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You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to upower in Ubuntu.
https://bugs.launchpad.net/bugs/1342341

Title:
  upowerd kills USB performance

Status in “upower” package in Ubuntu:
  New

Bug description:
  After launching Kubuntu and logging in to KDE I mount a USB storage
  device to e.g. /mnt/tmp and try the following command:

  dd if=/dev/zero of=/mnt/tmp/testfile bs=16M count=100

  I don't wait until it finishes, because when I press Ctrl+C, it waits
  several more seconds and prints that it has copied only one record and
  the speed was from 200 kB/s to 1.8MB/s, which is nowhere near the
  speed the device can operate.

  On the other hand, if I rename /usr/lib/upower/upowerd and restart,
  the same command finishes in under a minute and says the speed was
  >30MB/s for USB3 and ~30MB/s for USB2 devices/ports.

  This hasn't happened on Kubuntu 12.04, but does happen on 14.04.
  Running powertop at the "Tunables" tab doesn't show any difference, so it doesn't look related to autosuspend or similar things.
  This also happens with Kubuntu 14.04 LiveCD, not only with the already installed system.

  I've tested this with 3 different USB devices: Transcend JF780 16GB
  (in USB 3.0 and 2.0 ports), OCZ ATV 8GB (USB 2.0 device) and Seagate
  SRD00F2 2TB (in USB 3.0 and 2.0 ports) with identical results.

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: upower 0.9.23-2ubuntu1
  ProcVersionSignature: Ubuntu 3.13.0-30.55-generic 3.13.11.2
  Uname: Linux 3.13.0-30-generic i686
  ApportVersion: 2.14.1-0ubuntu3.2
  Architecture: i386
  CurrentDesktop: KDE
  Date: Wed Jul 16 00:29:34 2014
  InstallationDate: Installed on 2014-05-26 (50 days ago)
  InstallationMedia: Kubuntu 14.04 LTS "Trusty Tahr" - Release i386 (20140416.1)
  SourcePackage: upower
  UpgradeStatus: No upgrade log present (probably fresh install)

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