kernel-packages team mailing list archive

[AZ <131094@xxxxxxxxxxxxxxxxxx>]

Thanks for driving this forward.

You argue from
> So let us make one thing clear, IMHO if something overloads your machine with disk I/O it has to stall it.

This is a bit tricky, because overload means that the machine will be
able not complete all task in the time given, i.e. tasks will accumulate
until the resources are exhausted. Though, we usually do not have this
situation on desktop machines. There we have tasks to do and want them
to complete as fast as possible, thought some tasks may take longer than
others. For example, copying a 5 GB DVD disk will take some minutes or
so, but refreshing the browser window or switching windows should never.
Overlay here would mean the user will turn of the machine and by a
windows licence.

So this bug is mostly about having too big delays in applications using
only a small bit of the available resources (like when switching back to
a libreoffice window) when some other applications (like background file
indexing) are asking for the remaining disk io resource capacities.

> Code improves to mitigate effects but can never be perfect for *ALL*
users at once (especially in the default config)

I do not agree. Desktop responsiveness was achieved with older ubuntu
versions on the given hw and is achieved with other operating systems
(windows) on a broad range of hardware. I believe desktop responsiveness
is something sufficiently specific a cpu and io scheduler can be tuned
to. Using cgroups and alike might help, but should be configured by
Ubuntu by default if necessary.

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https://bugs.launchpad.net/bugs/131094

Title:
  Heavy Disk I/O harms desktop responsiveness

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: linux-source-2.6.22

  When compared with 2.6.15 in feisty, heavy disk I/O causes increased
  iowait times and affects desktop responsiveness in 2.6.22

  this appears to be a regression from 2.6.15 where iowait is much lower
  and desktop responsiveness is unaffected with the same I/O load

  Easy to reproduce with tracker - index the same set of files with
  2.6.15 kernel and 2.6.22 kernel and the difference in desktop
  responsiveness is massive

  I have not confirmed if a non-tracker process which does heavy disk
  i/o (especially writing) replicates this yet - will do further
  investigation soon

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