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From: "cbfalconer AT maineline DOT net" <cbfalconer AT att DOT net>
To: djgpp-workers AT delorie DOT com
Subject: Re: gcc-4.3. snapshots and DJGPP memory allocator efficiency
Date: Thu, 06 Dec 2007 02:43:33 +0000
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Reply-To: djgpp-workers AT delorie DOT com

Andris Pavenis wrote:
> 
> There seem to be serious performance problems in GCC-4.3 for DJGPP
> due to slowness of free() call especially for Ada compiler.
> 
> Tried to bootstrap gcc-4.3-20071130 for DJGPP (after reverting some
> earlier changes in libiberty/configure.ac present in snapshot).
> Initially thought that compiler  (gnat1.exe) has went into some
> infinite loop when compiling gcc/ada/ali.adb for stage2.
> 
> Found that extremly long time is being spent in libibrty/hashtab.c
> in procedure htab_delete() which in that case uses free() to
> release several millions allocated memory block. htab_delete()
> took perhaps about 30 minutes on Intel Core 2 Quad 2.4GHz processor
> (I did not measure accuratelly). There is of course not much use of
> 4 processor cores as DJGPP cannot use them all.

This sounds like the O(n) free is biting.  This is solved (O(1)) in
nmalloc for DJGPP, available on my page at:

   <http://cbfalconer.home.att.net/download/nmalloc.zip>

The version in that file has a terminal section, useless, for
allocating large aligned blocks.  The debuggery possibilities, and
linkage, are all done and in the manual.

I have some ISP problems with mail sending (receive is fine).  So
I prefer to use news:comp.os.msdos.djgpp.  Send any emails to my
address in sig below please, or the newsgroup.

-- 
 Chuck F (cbfalconer at maineline dot net)
   <http://cbfalconer.home.att.net>
   Try the download section.