Kenwood HP 9000 manual Making Shared Libraries Non-Writable, Using the +ESlit Option to cc, 148

	Creating and Using Libraries
	Creating Shared Libraries
	y.o
	d.o
	Notice that d.o is now closer to x.o and y.o, which call it. However, this
	is still not the best information to use because a.o and b.o are
	separated from x.o and y.o by the module e.o, which is not called by
	any modules. The actual optimal order might be more like this:
	a.o b.o x.o y.o d.o e.o
	Again, the use of lorder and tsort is not perfect, but it may give you
	leads on how to best order the modules. You may want to experiment to
	see what ordering gives the best performance.
	Making Shared Libraries Non-Writable
	You may get an additional performance gain by ensuring that no shared
	libraries have write permissions. Programs that use more than one
	writable library can experience significantly degraded loading time. The
	following chmod command gives shared libraries the correct permissions
	for best load-time performance:
	$ chmod 555 libname
	Using the +ESlit Option to cc
	Normally, the C compiler places constant data in the data space. If such
	data is used in a shared library, each process will get its own copy of the
	data, in spite of the fact that the data is constant and should not change.
	This can result in some performance degradation.
	To get around this, use the C compiler's +ESlit option, which places
	constant data in the $LIT$ text space (or in 64-bit mode, in a .text text
	segment) instead of the data space. This results in one copy of the
	constant data being shared among all processes that use the library.
	This option requires that programs not write into constant strings and
NOTE
	data. In addition, structures with embedded initialized pointers won't
	work because the pointers cannot be relocated since they are in read-only
	$TEXT$ space. In this case, the linker outputs the error message
	"Invalid loader fixup needed".

148 Chapter 5