RAM & Swap & Speed

[Jon Radel]

Jon Radel wrote:
> herbert langhans wrote:
>> Hi Daemons,
>> recently I had to add some more RAM on a workstation. Was 512MB before and is 2GB now, the reason was to give some graphic apps more space.
>>
>> But to my surprise the workstation ran faster--but before adding RAM it did NOT make use of the swap-partition and after the big RAM chip of course not too (checked it with #top).
>>
>> This was a Slackware installation. Had anyone experienced such effect on BSD as well? 
> 
> Why are you asking about Slackware file caching on a FreeBSD mailing
> list?  :-)
> 
> In any case, what you're probably seeing is the effect of having lots of
> spare RAM to cache files.  In FreeBSD top look at the Cache and Buf
> values up top.  If you're doing a lot of file I/O, this can make a
> noticeable difference, particularly if you're repeatedly reading the
> same files.

It has been pointed out that this response by me is incomplete, arguably
misleadingly so.  See
http://lists.freebsd.org/pipermail/freebsd-performance/2004-April/000769.html
for much more technical detail on what is really happening.

--Jon Radel
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