WINDOW HACK (WAS Re: Opening Office attachments in X and Classic)

[Allen Watson]

Title: WINDOW HACK (WAS Re: Opening Office attachments in X and Classic)

I am working on a 300 MHz iBook with its max of 320 MB RAM, and I don't find things terribly slow. Windows and focus are slower than in 9, yes, but nearly everything else is about the same. Complex Word macros are also slower in X, but that may have to do with window redrawing and refreshing...

Oh, one thing! Way back, I installed a hack from somewhere that activated a window feature Apple had disabled in the mistaken belief it was causing crashes; later, the cause was traced to something else. I don't know if that hack is now in 10.1.2 or not...or whether it got carried over from 10.1.1 when I updated. But it is related to compression of non-active windows, and I found that it speeded things up for me by freeing memory. I got the info from MacFixit. It was originally posted by Andrew Welch of Ambrosia Software, and apparently was still effective for 10.1.1.

Window Buffer Compression: Performance Increase      

This was being discussed over at MacNN. Give this hack a try...I noticed a significant performance increase on my Rev A iBook with 160 MB RAM. I noticed a significant drop in pagein/pageouts. NOTE THIS DOES WORK FOR 10.1.1 AS IT IS STILL NOT ENABLED BY DEFAULT. Here is the unedited text:

The window server has a cool feature in OS X 10.1 that isn't enabled by default (though it will be in an upcoming update, as I understand it): window buffer compression.

A little background. Under OS X, the contents of each window are saved in a buffer, so that they can be updated instantly, and also so that the cool transparency effects in Aqua are possible. This is a good thing, to have a fully buffered window manager -- however, it uses a lot of memory.

In 32 bit mode ("Millions" in System Preferences), a window that is 800 pixels wide by 600 pixels high uses up 1.9mb of RAM. When you consider that there are usually over 100 windows open when you're using OS X (not all windows are visible), you start to realize that this can start to add up in terms of RAM usage.

The more windows you open, the more RAM they use up, the more that virtual memory will have to page in and out while you use your applications to do work. This can cause slow-downs as the disk grinds to do the virtual memory paging.

So what Apple did was they implemented a compression mechanism into the window server. When a window's contents haven't changed for a given period of time, the window server compresses them, so they take up less memory. Since it uses a compression method that doesn't require the buffer to be fully decompressed to do compositing (dragging a window around, updating the screen, etc.), you won't notice a slowdown with this compression turned on.

In fact, because less memory is being used up by the window buffers, more RAM will be available for your applications, with will mean less virtual memory paging, and may in fact result in speeding up your machine. Additionally, since less data needs to be read (it is compressed, after all!), things like updating windows may be faster as well.

If you are a power user who has lots of windows open, you might consider giving this hack a shot. I'm using it, and getting compression ratios of about 8.5:1 (in other words, my window buffers are using 8x less RAM than they normally would).

Now then, onto the hack! First, open up the Terminal application (found in /Applications/Utilities/) and type:

sudo pico /library/preferences/com.apple.windowserver.plist

(you'll need to enter your admin password in order to proceed)

Move the cursor down below the first <dict> tag, and paste the following text in:

<key>BackingCompression</key>
<dict>
<key>compressionScanTime</key>
<real>5.000000000000000e+00</real>
<key>minCompressableSize</key>
<integer>8193</integer>
<key>minCompressionRatio</key>
<real>1.100000023841858e+00</real>
</dict>


Then hit Control-X to exit pico (hitting the Y key to save the changes before exiting when it asks you), then log out and back in again, and ta da! Compressed window buffers. Enjoy...

On or near 1/9/02 12:37 PM, Jeffrey Kain at [EMAIL PROTECTED] observed:

> At 1/9/2002 03:27 PM, you wrote:
>
>> I find that it's chiefly switching windows and focus that's slow. Other
>> things, such as running identical applescripts, go faster in X. I _do_ have
>> a lot of memory - 768 MB, and I think that makes a huge difference. OS X
>> needs a lot of RAM.
>
> Yes, memory definitely helps, and X is nice on my 733 MHz G4 with 4x AGP
> graphics at home. It's not so nice on my 500 MHz G4 (upgraded Blue/White G3
> with PCI graphics) here at work, even with 704 MB of (PC100) memory.
>
> Jeff
>

--
Microsoft MVP for Entourage/OE/Word
Allen Watson <[EMAIL PROTECTED]> XNS name: =Allen Watson
Applescripts for Outlook Express and Entourage: <http://homepage.mac.com/allenwatson/>