Subject: Re: UVM is HUGE!
To: David Jones <>
From: Jason Thorpe <>
List: current-users
Date: 02/08/1998 11:14:04
On Sun, 8 Feb 1998 11:51:59 -0500 (EST) 
 David Jones <> wrote:

 > Linux VM: 33K.
 > Mach/4.4 VM: 45K.  This VM system was derived from a microkernel implementation
 >   that tried to be much more general, so I can understand the slight increase
 >   in code size.
 > UVM: 144K.
 > Yowww!!!  Any reason for this?  Do we have large static tables in the code
 > segment (I ignored the data segment)?  Can I expect three times the 
 > functionality and performance?

There's a _very_ good reason for this :-)

Until today, UVM logged every action it performed by default.  This means that
there's a fair chunk of object code dedicated to these logging functions,
string constants, etc.

Matt Green committed a change that turns off the logging by default.  This
should shrink the object size and improve performance.

UVM also uses inlines extensively (look at the uvm_*_i.h header files).

UVM also does have additional functionality, e.g. the page loanout stuff.
That will account for some of it.

Jason R. Thorpe                             
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