dgux_notes

减少内存碎片的malloc分配函数

Date: Sun, 15 Aug 1999 22:29:56 -0700 (PDT)
From: Takis Psarogiannakopoulos
Subject: DG/UX dmalloc

Dear Gray,

I am writing this relating to the DG/ux port (ix86) of dmalloc
library. I am responsible for the DG/ux X11R6.3 and I am designing a
new Xserver with multiple threads, so I want to use your dmalloc, as a
replacemnet for the crap system DG/ux library.  I am curious who wrote
to you that dmalloc (as is) will work in DG/ux. Firstly the threads
library for DG/ux "-lthread ", (configure , configure.in) should be
something like

	AC_CHECK_LIB(thread, __d10_pthread_mutex_init, LIBTHREAD="-lthread"
	   DG_THREAD_FLAG="-D_POSIX4A_DRAFT10_SOURCE")

(there is no pthread_create , pthread_mutex_init or ...  inside
-lthread)

and the functions sould be detected by , say,

	AC_CHECK_FUNCS(__d10_pthread_mutex_init) ...etc

As the DG/ux header pthread.h is _not_ a desent one , we need probably
to define somewhere (in conf.h.in ?) something like

	#if defined(DGUX)
	#include <pthread.h>
	#define _USING_POSIX4A_DRAFT10 1
	#endif

and then 

	#define __d10_pthread_mutex_init mutex_init 

etc ... (for the others).

Also in the above AC_CHECK_LIB(thread ...)  to add (for the _d10__xxx
of DG/ux) a special flag like

	DG_THREAD_FLAG="-D_POSIX4A_DRAFT10_SOURCE" 

(as I did already)

which we want to append in the Makefile as

	AC_SUBST(DG_THREAD_FLAG)

and add it to the standard CFLAGS as 

	DG_THREAD_FLAG = @DG_THREAD_FLAG@

CFLAGS = ... $(DG_THREAD_FLAG) 

so it will be empty for other OS ...

I confess these are not great changes, but as dmalloc is it will not
detect lthread, and also neither of the pthread functions!

Finnaly the correct CFLAGS for DG/ux are

	-DDGUX -D_DGUX_SOURCE -D_POSIX4A_DRAFT10_SOURCE

but I guess one can pass these to configure when it executes
it. However looking for the header dg_sys_info.h (which obviously is a
DG/ux particular header , not in any other OS) like

	AC_CHECK_HEADER(dg_sys... )

we can have in the configure.in something like $ac_is_dgux=yes,no and
accordingly set the DG/ux CFLAGS, so the user doesnt need to know the
correct configuration command.  If you want me to submit a patch drop
me an e-mail.

Regards,
Takis