Subject: Re: trying to compile emacs under cygwin
From: Joe Buehler <[email-masked]>
To: [email-masked]
Date: Fri, 28 Mar 2003 09:23:06 -0500

Robert Mecklenburg wrote:

> Static heap usage: 2129280 of 10648960, slop is 65536 -- 8320k wasted -- reset to 2194816k
> emacs: SHEAP_ADJUSTMENT needs to be modified to reduce memory waste!

You increased the heap size, but it's outside the fuzz range -- you
are over it by about 8 MB.  Emacs would run, but the problem is that
the binary would be a lot larger than it needs to be.  Under Cygwin,
this is an issue because of the way that fork() works.

So what you have to do is increase SHEAP_ADJUSTMENT by enough that
you end up in the comparison fuzz range.

> actually writes sheap.c, so I edit the script to change the -620000
> to:
> 
> +#ifdef HAVE_X_WINDOWS
> +#define SHEAP_ADJUSTMENT 2194816 /* XEmacs does this dynamically */
> +#else
> +#define SHEAP_ADJUSTMENT 2194816 /* XEmacs does this dynamically */
> +#endif

That's the correct thing to do.  Edit the build script -- it patches
the original emacs source for Cygwin.

What you want to do is look at the message you get after you compile:

Static heap usage: 2129280 of 10648960, slop is 65536 -- 8320k wasted -- reset to 2194816k

And figure out what to set SHEAP_ADJUSTMENT to based on how the first two numbers
compare.  The message says that you used 2129280 bytes out of 10648960 available,
so decrease SHEAP_ADJUSTMENT by (10648960 - 2129280).  SHEAP_ADJUSTMENT will be some
negative number because the base heap size is 8 MB, and emacs doesn't need anywhere
near that.

If it helps any, this piece of code hurts my head also -- I have no idea why it
is set up to be so complicated.  But it works!
-- 
Joe Buehler

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