Re: [SLE] empty the swap partition? slow internet

From: John Sowden (jsowden_at_americansentry.net)
Date: 04/25/05

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    To: suse-linux-e@suse.com
    Date: Sun, 24 Apr 2005 15:56:08 -0700
    
    

    On Sunday 24 April 2005 15:31, Randall R Schulz wrote:
    > Carlos, John,
    >
    > On Sunday 24 April 2005 05:36, Carlos E. R. wrote:
    > > The Saturday 2005-04-23 at 20:35 -0700, John Sowden wrote:
    > > > I am running a 48MB 133Mhz machine with Suse 8.0
    > > > It has worked fine on the net until today. The spped slowed down
    > > > often to less than 100 bytes per second, and the hard drive
    > > > thrashed for hours.
    > > >
    > > > Questions:
    > > > Should the swap partition be empty upon cold boot? If so what is
    > > > the command to test it to see how full it is, and to empty it, and
    > > > in which boot file should it go?
    > >
    > > There is no such thing, and no need either. Your problem must be
    > > something else.
    > >
    > > > It took me 8 hours to look at about 30 web pages of a ecommerce
    > > > site. I never was able to make my purchases. Sometimes, it would
    > > > take 15 minutes to bring a page up. more ram is an easy answer,
    > > > but this is an old machine, and 48MB is overkill for other work.
    > > > what has changed?
    > >
    > > My guess is that those pages are using java, and java needs a lot of
    > > memory. As you don't have it, it swaps a lot. I had the same problem
    > > three years back, and had to upgrade the computer, no other way:
    > > memory for old computers is prohibitive.
    >
    > As a blanket statement, "Java [software] needs a lot of memory" is not
    > particularly accurate.
    >
    > As a Java programmer who has worked on some programs that _do_ use a lot
    > of memory (by their nature, whether implemented in Java or something
    > conventionally thought of as more parsimonious), I've noticed that when
    > the program's demand for memory approaches the limit imposed by the
    > Java Virtual Machine at the time it was launched, performance degrades
    > very badly. This happens because the JVM must perform more and more
    > garbage collection. This will not lead to swapping unless the Java heap
    > limit is set large enough to cause the OS in which it's running to
    > page. The default JVM heap limit won't do that on any system that's not
    > already on the brink of thrashing.
    >
    > However, I now look back and see that John says "48 MB is overkill."
    > From that perspective, Carlos is right. You'll have trouble running
    > non-trivial Java code with so little RAM. In fact, I don't see how
    > you're running a GUI environment of any sort in so little RAM.
    >
    > Generally speaking, the solution to such a problem with Java software is
    > to increase the JVM maximum heap size by specifying the -Xmx<size>
    > option, but I don't know how to do that for applets running within a
    > browser.
    >
    > John, which browser and which JVM release are you using?
    >
    > > Carlos Robinson
    >
    > Randall Schulz

    First, thanks for all the feedback.

    I am running the Konq that came with Suse 8.0.
    I do not know which JVM I am running, but I did not install it,
    so I assume it is the one that came with Suse 8.0.
    If you tell me how, I will check that (and learn how at the same time!)
    re: 48MB is overkill _for other work_, I was referring to MS-DOS 7.0 that I
    use on the other computers in our office, and this one (boots DOS/Linux), as
    well as my 128MB 1.3GHz Suse 8.2 machine (also boots DOS/Linux). I run our
    mission critical and business stuff on DOS, although I am in the process of
    re-writing all spreadsheets to open office.
    re: this thrashing issue, it seems to happen after I have been on the net for
    several hours, not when the machine is first turne on. Also I went back to
    the electronics supplier site (mpjs.com) after shutting off the machine. It
    degraded after about 15 minutes.

    ---
    John Sowden
    American Sentry Systems. Inc.
    1221 Andersen Drive
    San Rafael, CA  94901
    U.L. Listed Central Station Alarm Service
    Serving the San Francisco Bay Area Since 1967
    mail@americansentry.net
    http://www.americansentry.net
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