Date: Mon, 8 Jul 2002 21:58:03 -0400 From: Brian T.Schellenberger <bts@babbleon.org> To: Chuck Robey <chuckr@chuckr.org>, FreeBSD Hackers List <freebsd-hackers@FreeBSD.ORG> Subject: Re: swap & huge mem systems Message-ID: <20020709015803.78FC1BA05@i8k.babbleon.org> In-Reply-To: <20020708212522.N945-100000@april.chuckr.org> References: <20020708212522.N945-100000@april.chuckr.org>
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On Monday 08 July 2002 09:30 pm, Chuck Robey wrote:
| Nowadays, what with the price of fast memory at such low levels, I'm
| buying more memory than I really need, just because it's *so* cheap, the
| price has gone up before, and it's possible (maybe likely) that next
| year's popular new app will need the memory. I'm probably not alone in
| doing this. It's causing me to wonder about how much swap to allocate.
|
| I used to follow the rule that I dedicate twice as much disk memory to
| swap as I have RAM. Now, with my new system, I'm getting a gig of RAM,
| but it seems ridiculous to dedicate 2G of disk to swap. Under these
| conditions, what's the real bottom limit (if you have one gig of RAM) for
| how much swap you can get away with? One Gig? Less?
The bottom limit is zero.
I ran with zero swap for a while; the only problem is that if an app goes
nuts and starts allocating unlimited memory it gets *all* the memory before
you can possibly intervene, so now I allocate some swap space just so that I
can see problems in xosview before they happen. If any swap is ever
allocated, then I know something's wrong and I have time to intervene before
the system is completely locked up.
I allocate 256M of swap. In fact, I think that a pretty good formula for a
workstation is probably
swap = MIN(2*RAM, 256M)
unless you have really massive applications for multiple users or something.
The only big drawback that I know of with this scheme is that if your system
panics you can't get a kmem dump because there's not enough space to hold it.
|
| ---------------------------------------------------------------------------
|- Chuck Robey | Interests include C & Java programming, FreeBSD,
| chuckr@chuckr.org | electronics, communications, and signal processing.
|
| New Year's Resolution: I will not sphroxify gullible people into looking
| up fictitious words in the dictionary.
| ---------------------------------------------------------------------------
|-
|
|
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--
Brian, the man from Babble-On . . . . bts@babbleon.org (personal)
http://www.babbleon.org
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