[SunRescue] Misc. Questions about my Ultra 10

[Ed Pate]

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Sorry it took so long to reply, my mail server has been PANIC'ing on me.  As soon as I get the
memory for my IPC, it's getting moved off Intel...

> --__--__--
>
> Message: 8
> From: "Christopher Byrne" <chris at chrisbyrne.com>
> To: <rescue at sunhelp.org>
> Subject: RE: [SunRescue] Misc. Questions about my Ultra 10
> Date: Mon, 4 Dec 2000 03:07:13 -0800
> Reply-To: rescue at sunhelp.org
>
> Eric,
>
> You are running into two classic UNIX issues, and a fun SunPCI issue. The
> first is caused by the way the kernel reports resource allocation and
> utilization
>
> Eric Ozrelic
> Sent: Monday, December 04, 2000 02:27
>
> >1. Using top, I notice that usually when I reach my cruising altitude with
> >application usage.. i.e I have everything open that I need, and am working,
> >my physical memory is at about 4MB free, and my swap has around 350MB free.
> >Is this normal? Do I have a memory leak?
>
> In actuality top doesn't report on the resources used, but the resources
> allocated for use. Many programs will reserve a large chunk of memory that
> they may or may not use. This chunk will be shown as used in utilities like
> top. Also It is appropriate behavior for your system to use almost all of
> it's physical RAM before it starts paging out significantly, since RAM is so
> much faster than swap.
>
> The second issue, about  the Sun PCI is once again a matter of resource
> allocation.
>
> >2. I use a SunPCi card and notice that as soon as I start using it, it
> sucks
> >up a TON of my memory, even though I have 256MB of memory onboard the card.
> What gives?
> >I'm running the newest SunPCI software.
>
> The way the kernel handles IO calls and what not for the SunPCI cards is
> very memory intensive, especially if you are using shared ethernet and
> shared display on the original SunPCI card. The new SunPCI-II is a lot more
> efficient, and has it's own  (reasonalby good) display and ethernet
> capabilites. Once again the lage amount of memory isn't really in use, it's
> been reserved by the kernel to act as a buffer for the SunPCI subsystems I/O
> (storage, display etc...)
>

Just a point I wanted to throw out...

Under Solaris, no memory pages are freed until freemem reaches a critical point AND some process is
requesting additional memory.  The reasoning behind this is to all of the pages that have been
released by processes as file cache in case those pages are needed sometime in the future.  The
memory is not so much "allocated", as much as just sitting there waiting for somebody to need it.
Granted, a lot of programs will request large amounts of memory, and some will "lock" some or all
of it into physical memory, but unless it is locked, it is eligible to get paged out.

All in all, the virtual memory system in Solaris is pretty elegant.

> <deleted the X stuff>
> Chris Byrne
> =======================================
> The eyes may be the windows on the soul
> But the word is the doorway to the mind
> =======================================
>
> --__--__--

Ed

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