Re: [tlug] Possible command to boost to laptop performance

[Marty Pauley <marty.pauley@example.com>]

On Tue, Nov 2, 2010 at 1:33 PM, Dave M G <dave@example.com> wrote:
>
> I find that on my Ubuntu laptop, running this when the memory and cache
> usage seems high (going by the memory/cache monitor graph Gnome panel
> applet) will cause the memory and cache to drop by half or more. Not
> always, but often enough. As a result, the laptop seems to perform
> better, as I think it's swapping less.

Are you measuring performance, or just guessing?  Can you give us some
indication of how much better it is performing?

I would have thought it would perform _worse_ just after you flush all
the cache, since the cache is there to improve performance.

Please be careful how you interpret the memory monitor information.
It's probably showing you details of free and used memory, but that
doesn't always mean the same as available and unavailable. Your
buffers and cache will appear as used, but if an application needs
more memory the kernel will drop some cache and give that memory to
the app.  For example, I have some file servers with 16 GB memory.
After they've been running for a few days the memory monitor shows the
memory as over 93% used.  Only around 7% of that is for applications;
the rest is cached filesystem data, and it's almost all clean since my
fileserver is mostly read-only.  So all that memory could be available
for application use if required.

When you run that command you are telling the kernel to drop all the
cache even though nothing needs it.  That should actually make
performance significantly worse.

-- 
Marty