Date: Tue, 8 Feb 2005 15:39:22 -0700 From: Pat Maddox <pergesu@gmail.com> To: Pat Maddox <pergesu@gmail.com>, freebsd-questions@freebsd.org Subject: Re: Inactive memory Message-ID: <810a540e050208143921cd416d@mail.gmail.com> In-Reply-To: <20050208222759.GA29360@falcon.midgard.homeip.net> References: <810a540e050208133310333144@mail.gmail.com> <20050208213612.GA29063@falcon.midgard.homeip.net> <810a540e050208134479b4e774@mail.gmail.com> <20050208222759.GA29360@falcon.midgard.homeip.net>
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Thanks a lot for the explanation. I think I can close top and stop
worrying now :)
On Tue, 8 Feb 2005 23:27:59 +0100, Erik Trulsson <ertr1013@student.uu.se> wrote:
> On Tue, Feb 08, 2005 at 02:44:39PM -0700, Pat Maddox wrote:
> > Alright, that lets me know that it's not an entirely bad thing. It
> > does say, however, that it's fine as long as the free memory isn't
> > REALLY low. It did get down to 13MB though, as I said.
>
> Don't worry. 13MB is not what I would consider as "REALLY low" (ok,
> with 1GB RAM maybe it is) but anyway, the only thing to worry about is
> if the system starts to swap very often - that means you need more memory.
>
> >
> > So now I understand that it's alright for the free memory to be low.
> > I don't understand how the inactive, cache, and buffered memory are
> > used though. When a process uses up all the free memory, does it then
> > use some from inactive, or does it use swap?
>
> Memory normally moves along the following path:
>
> Wired -> Active -> Inactive -> Cached -> Free
>
> and then when it gets allocated and used it moves back to Wired.
>
> The difference between the categories is mainly that "Inactive" and
> "Cached" memory still contains data that the system might be able to
> reuse, while "Free" memory is completely free and unused.
> In order to use Cached or Inactive memory it might need to be flushed
> first, with Inactive probably being dirty and Cached probably not.
> ("Active" memory is almost certainly dirty and is therefore somewhat
> more expensive to reuse.
>
> If you didn't understand the preceding paragraph, don't worry. It is
> not really important to understand.
>
> For most purposes you should just consider all of "Free", "Cached", and
> "Inactive" to be free memory that is available for allocation.
>
>
> >
> >
> > On Tue, 8 Feb 2005 22:36:12 +0100, Erik Trulsson <ertr1013@student.uu.se> wrote:
> > > On Tue, Feb 08, 2005 at 02:33:14PM -0700, Pat Maddox wrote:
> > > > I've always got a lot of inactive memory on my machine, around 520MB
> > > > or so. While doing a portupgrade, the free memory dropped to around
> > > > 13MB. I'm just curious what exactly the inactive memory is. Will the
> > > > OS use the inactive memory before dipping into swap? Or is that
> > > > memory off limits now? If so, is there any way to free it up? I've
> > > > got 1GB total on the machine.
> > >
> > > http://www.freebsd.org/doc/en_US.ISO8859-1/books/faq/misc.html#TOP-FREEMEM
>
> --
> <Insert your favourite quote here.>
> Erik Trulsson
> ertr1013@student.uu.se
>
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