Re: RAM freimachen?

From: Malte von dem Hagen <DocValde(at)>
Date: Tue, 10 Jun 2003 14:00:40 +0200

Hallo Marian Hettwer,
am Dienstag, 10. Juni 2003 um 13:53:48 schrieben Sie:

> Hallo Malte,

>>@Liste: Vielleicht eine gute Gelegenheit für einen Link oder eine kruze
>>Erklärung des FreeBSD-RAM-Konzeptes.
> gute Idee, würd ich auch gern was drüber lesen ...

Hab grad mal selbst was gefunden :-) Look here:

16.1. FreeBSD uses far more swap space than Linux. Why?

FreeBSD only appears to use more swap than Linux. In actual fact, it does
not. The main difference between FreeBSD and Linux in this regard is that
FreeBSD will proactively move entirely idle, unused pages of main memory
into swap in order to make more main memory available for active use.
Linux tends to only move pages to swap as a last resort. The perceived
heavier use of swap is balanced by the more efficient use of main memory.

Note that while FreeBSD is proactive in this regard, it does not
arbitrarily decide to swap pages when the system is truly idle. Thus you
will not find your system all paged out when you get up in the morning
after leaving it idle overnight.

16.2. Why does top show very little free memory even when I have very few
programs running?

The simple answer is that free memory is wasted memory. Any memory that
your programs do not actively allocate is used within the FreeBSD kernel
as disk cache. The values shown by top(1) labeled as Inact, Cache, and
Buf are all cached data at different aging levels. This cached data means
the system does not have to access a slow disk again for data it has
accessed recently, thus increasing overall performance. In general, a low
value shown for Free memory in top(1) is good, provided it is not very



PS: Dennoch sind ergänzende Worte natürlich immer erwünscht :-)

Malte von dem Hagen
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Received on Tue 10 Jun 2003 - 14:00:11 CEST

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