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Date:      Sun, 31 Oct 1999 14:38:14 -0800
From:      "Scott Hess" <scott@avantgo.com>
To:        "Michael Beckmann" <petzi@apfel.de>
Cc:        <hackers@FreeBSD.ORG>
Subject:   Re: Limitations in FreeBSD
Message-ID:  <199801bf23f0$9e4af920$1e80000a@avantgo.com>
References:  <19991029011348.B2757@apfel.de> <199910282253.PAA02302@dingo.cdrom.com> <19991029020253.A3005@apfel.de> <15f901bf219e$20df55c0$1e80000a@avantgo.com> <19991029024742.B3005@apfel.de>

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Michael Beckmann <petzi@apfel.de> wrote:
> On Thu, Oct 28, 1999 at 04:42:42PM -0700, Scott Hess wrote:
> > Urk!  I don't mean to be insulting, but the notion that you would roll
> > _any_ solution out for a problem of this size based on word of mouth
freaks
> > the crap out of me.
>
> Hey ! You guys seem to have pretty strict opinions about how to solve
problems.
> Right now I am just investigating the options and asking for the
properties of
> this FreeBSD OS (where news is not the only reason for finding out about
them).

Well, I didn't mean that to come off as a "Don't bother me until you've
done your homework" response.  Let's put my point another way.  There are
certainly sites out there running full newsfeeds on Intel-based hardware.
I have zero concerns about FreeBSD being in any way a limiting factor at
that point.  [Likewise, I have zero concerns about Linux being the limiting
factor.]  INN isn't being developed for ultra-high-end systems, after all.
You might easily be able to configure up a system where you can use more
file descriptors than FreeBSD can handle well, or more mbufs, or more of
some other resource, but after inspection it will turn out that there are
other configurations which give the same performance without tickling the
same problems (you can read that as a general thing, on the order of "Just
because 100 file descriptors is better than 25 doesn't mean that 10,000 is
better than 100").

Besides, there have got to be hundreds of people out there running big
newsfeeds on FreeBSD.  Unfortunately, you'll probably get more responses
with specific questions about a problem you're having than you will with
general questions about problems you might or might not have.

> > and enough users that mmap'ed I/O in nntp is needed and the number of
file
> > descriptors is going to be a problem, and you're willing to change
>
> I would like to know if that number of file descriptors is going to be a
> problem, could someone tell me please ? It appears that 2^17 are settable
> through sysctl, but will I actually be able to use that many ? (Yes, I
could
> write a tool to find it out, but I am willing to rely on word of mouth
here).

I, personally, would never configure a system that required 100k file
descriptors, regardless of whether that many filedescriptors appeared to
work or not.  On the other hand, 10k file descriptors doesn't scare me
(though I'd be uncomfortable with the notion of that being an _average_
rather than a maximum), and I would be quite surprised if you had problems
with periodic forays out to 100k.  Unfortunately, I'm well into arm-waving
at that point, because I don't actually _know_, because as I mentioned, I
wouldn't feel comfortable out there...

Good luck,
scott




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