Subject: Re: YDL seems a little slow
From: Timothy A. Seufert (tas@mindspring.com)
Date: Mon Nov 12 2001 - 15:00:15 MST
At 10:53 PM -0600 11/11/01, Dana Robinson wrote:
>Group,
>
>I have YDL 2.0 running on my 7500 with a 260 MHz G3 upgrade card and 96
>Mb of RAM. It works fine, but I've noticed that it seems a little slow.
>It takes forever to log on, applications seem to take a long time to start
>and compiling takes longer than I would expect.
>
>Recently, I installed RHL 7.2 on a Pentium 166 with 64 Mb of RAM. It
>seemed much more responsive. Logging on, in particular, took a lot less
>time. Both the Pentium and the Mac are similiarly configured and are very
>lightly loaded - neither runs any heavy-duty servers or anything.
>
>I spoke with a friend of mine who is much more knowledgable in the ways of
>Macs, and he said it might be the G3 card that I have. He says that the
>G3 upgrades are a mixed bag with regards to compatability. Is this true?
Upgrades for the 7500 should generally be fine.
One thing you have to watch for is whether your L2 cache is getting
enabled. The computers which shipped with a G3 enable the cache
before any OS starts booting, but the firmware in older upgraded
machines doesn't know the G3's backside L2 even exists.
If you use BootX to boot Linux, and the G3 upgrade extension loads
before the BootX extension does, you're good to go. Otherwise, you
need to boot into MacOS and use a utility supplied with BootX to grab
the correct G3 cache setting so that BootX can enable it before
loading Linux.
If you use quik, I don't know what the preferred method is, but there
is a kernel command line option to set L2CR (the L2 cache control
register in the G3). Just supply "l2cr=VALUE" where VALUE is
whatever the G3 utility you use does in MacOS.
>Could it be something else? Is the linux kernel for PPC just not as
>optimized for PPC since it's newer and has fewer people working on it?
To some extent, but nowhere near bad enough that a Pentium 166 should
outperform a G3 260. It should keep up with a Pentium II at roughly
the same clock rate. (actually it should be somewhat faster than a
PII.)
>Do I need more memory on a PPC than on Intel hardware?
Somewhat, but not a lot. PowerPC binary code takes up more memory as
a general rule (most RISC processors have lower code density than
CISC). But data is generally the same, and you usually have more
data in memory than code.
>I plan to build a
>custom 2.4 kernel on it this week to see if that helps. Maybe if I clean
>out some of the genero-build junk it will be a little more nimble.
Doubtful. For the most part a generic build just means that more
drivers are built. Unused drivers don't use any CPU time. If built
into the kernel, they may cost some memory, but not that much.
-- Tim Seufert
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