Package: general
Severity: wishlist

I have been plagued by long delays with an unresponsive laptop,
waiting for it to swap in Eclipse for several minutes at a time,
several times per day. This is a Thinkpad T61 with 4 GB of RAM,
squeeze/sid, X.org, KDE and Eclipse. (4 GB ought to be enough for
everyone, right?)

Recently I got the advice [1] to set vm.swappiness to 0, rather than
the default 60. This improved things dramatically. Apparently Eclipse
is no longer being swapped out preemptively all the time. The
difference in perceived responsiveness is spectacular.

Shouldn't we provide a lower swappiness by default for desktop
installs, at least those with a fair amount of RAM? This could improve
the user experience on most modern desktop systems. Most users will
probably never find out to tune this on their own. Ubuntu recommends a
value of 10 for desktop systems [2, 3] (but ship with the default
value).

I realise that I don't have any solid evidence that this is a good
move, maybe others can fill in with their experience. The goal here is
to improve desktop responsiveness when multi-tasking, especially on
machines with reasonably large RAM and one or more large applications.

[1] http://lists.debian.org/debian-kde/2010/05/msg00313.html
[2] <https://help.ubuntu.com/community/SwapFaq#What is swappiness and how do I change it?>
[3] http://brainstorm.ubuntu.com/idea/5481/

-- System Information:
Debian Release: squeeze/sid
APT prefers testing
APT policy: (990, 'testing'), (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.33.2-melech (SMP w/2 CPU cores; PREEMPT)
Locale: LANG=sv_SE.UTF-8, LC_CTYPE=sv_SE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash



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On 5/12/2010 1:22 PM, Marcus Better wrote:
> Recently I got the advice [1] to set vm.swappiness to 0, rather than
> the default 60. This improved things dramatically. Apparently Eclipse
> is no longer being swapped out preemptively all the time. The
> difference in perceived responsiveness is spectacular.

You might also be interested in:

# sync; cat 3 > /proc/sys/vm/drop_caches

This is a nondestructive operation that will drop your clean caches,
clear up unused inodes, and free up available RAM. Usually, after
running my desktop for a few hours, depending on the applications I'm
running as well, this will free up about 1/2 of my installed RAM.

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O O O . O . . O O O O . O O O

On 2010-05-25, Aaron Toponce <aaron.toponce@gmail.com> wrote:
> On 5/12/2010 1:22 PM, Marcus Better wrote:
>> Recently I got the advice [1] to set vm.swappiness to 0, rather than
>> the default 60. This improved things dramatically. Apparently Eclipse
>> is no longer being swapped out preemptively all the time. The
>> difference in perceived responsiveness is spectacular.
> You might also be interested in:
>
> # sync; cat 3 > /proc/sys/vm/drop_caches
>
> This is a nondestructive operation that will drop your clean caches,
> clear up unused inodes, and free up available RAM. Usually, after
> running my desktop for a few hours, depending on the applications I'm
> running as well, this will free up about 1/2 of my installed RAM.

Why would I want to drop my caches? In fact I even use Tux on Ice for
hibernation so that I can keep my buffer cache, otherwise it takes ages
for the buffer cache to be loaded in after restore...

Kind regards,
Philipp Kern


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