Re: New computer planned

[Martin Steigerwald <Martin@lichtvoll.de>]

Am Montag, 20. Februar 2012 schrieb Ralf Mardorf:
> On Mon, 2012-02-20 at 10:17 -0500, Allan Wind wrote:
> > Memory is cheap.  More is better as Linux uses it for disk cache 
> > if nothing else.
> 
> For heavy audio production I never noticed that even the swap gets
> touched with 4GB RAM.

That does not give any clue whether Linux would use more RAM as disk cache 
if it had it. Linux might not touch swap yet even when it would utilize 
more RAM for disk caching and thus be faster with more RAM.

Well lets have a closer look on a 8 GB machine:

martin@merkaba:~> free -m 
             total       used       free     shared    buffers     cached
Mem:          7783       4559       3223          0        201       1082
-/+ buffers/cache:       3275       4507
Swap:        12287        282      12005

Already here Linux utilizes more than 4 GB of RAM. But it doesn´t use all 
8 GB of RAM, not even for disk caches. But after waking up from 
hibernation to disk it was not running for long today.

One KDE 4.7.4 session, Kontact, KMail, some other small apps.

Now I start LibreOffice Writer 3.4.5 and Iceweasel 10:

martin@merkaba:~> free -m
             total       used       free     shared    buffers     cached
Mem:          7783       4891       2891          0        202       1302
-/+ buffers/cache:       3386       4397
Swap:        12287        281      12006

Linux continues to utilize even more memory.

Minus caching already 3,3 GB RAM is in use. So with 4 GB RAM there would 
not be much space for disk caching. Granted that some applications might 
be less greedy with memory allocations when not so much of it is 
available.


So while 4 GB would work for a KDE session with some apps, heck even 2 GB 
would work, 8 GB should give some performance boost - possibly rather 
little, considering that the Intel SSD 320 in that ThinkPad T520 is quite 
fast for an SATA 300 SSD. But still RAM is an order of magnitude faster. 
10 times at least compared to an SSD. More than that for a harddisk.

Given the price of RAM I would put 8 GB in for 64 bit Linux. At least I 
would make sure that I have the option to do it later. Which should be 
true for any recent desktop/tower motherboard - when its not for Atom or 
something like that.

-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7