Date: Tue, 8 Oct 2002 12:10:39 -0700 (PDT) From: Nate Lawson <nate@root.org> To: "Vladimir B. Grebenschikov" <vova@sw.ru> Cc: arch@FreeBSD.org Subject: Re: using mem above 4Gb was: swapon some regular file Message-ID: <Pine.BSF.4.21.0210081209010.11243-100000@root.org> In-Reply-To: <1034094238.899.14.camel@vbook.express.ru>
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On 8 Oct 2002, Vladimir B. Grebenschikov wrote:
> χ Tue, 08.10.2002, Χ 19:50, Mikhail Teterin ΞΑΠΙΣΑΜ:
> > On Tuesday 08 October 2002 11:41 am, Terry Lambert wrote:
> > = Terry Lambert wrote:
> > = > So whatever connections you are getting now... halve that, or less,
> > = > to get a window for your RAM disk (you will need KVA for mappings
> > = > for all the memory that *can* be in the window, etc.).
> > =
> > = To emphasize this: if you are using 4K pages, you will need:
> > =
> > = 4K/1M * 64G = 256M
> > =
> > = ...1/4 of 1G of memory outside the window, just for page tables.
> > =
> > = Also, if we still were using an mbuf per connection for the
> > = template, for 1,000,000 connections, that's 256M of RAM -- another
> > = 1/4 gig.
> >
> > = Yeah, most people don't think in these terms; personally, I like
> > = to call it "Extreme BSD". 8-).
> >
> > Although this is fascinating read -- it getting further and further away
> > from the original subject. And from the modified one too -- I don't
> > believe Vladimir said anything about networking...
>
> Exactly, Terry is right about large number of relative-small
> network-access processes (say apaches). But there are some other cases,
> say you have some DB server with huge index, say 10Gb, I think keep
> index in RAM effective than on disk.
It's often surprisingly effective to just access the index on disk and
tune your VM cache instead. You can lose performance by double-caching
data.
-Nate
You teach a child to read and he or her will be able to pass a literacy test.
-- President Bush, 2/21/2001
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