From kde-devel  Thu Feb 28 19:29:27 2002
From: Kuba Ober <kuba () mareimbrium ! org>
Date: Thu, 28 Feb 2002 19:29:27 +0000
To: kde-devel
Subject: Re: About memory allocation failures....
X-MARC-Message: https://marc.info/?l=kde-devel&m=101492461616717

> > A lot of memory in kde apps running on multiuser servers is wasted to
> > store same things over and over....  I did a full memory dump once on
> > big system running many kde user sessions, and whooping 7% of pages
> > (and page-sized memory chunks, as all offsets were tested) had exact
> > duplicates, and about 20% had duplicates with small differences only -
> > loader fixups :-(( These are resident, live, physical in-ram pages,
> > I'm not talking about swap. All of these pages were owned by kde
> > processes (applications).
>
> Hmm, I thought the OS would have merged the duplicate pages, but of
> course it can't with ones that have small differences. Any ideas how
> that could be fixed ? I'd be interested to hear if it's just a gcc bug,
> or if there's some complex problem behind it, and whether it's FreeBSD
> specific or if it happens on Linux too.

I'm clueless about details. I don't even know how did the duplicate pages got 
created in the first place - I assume that they were empty pages, or somesuch 
first, and got written to by different processes. No kernel I know of does 
really try to merge pages after they have been written to...

As to the other points, I'll reply time permitting.
Cheers,
Kuba
 
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