Date: Tue, 4 Nov 1997 12:39:58 +0800 (GMT) From: Orlando Andico To: "John M. Aldrich" cc: djgpp AT delorie DOT com Subject: Re: DJGPP and Linux In-Reply-To: <345ECC69.7FA4@cs.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Precedence: bulk On Tue, 4 Nov 1997, John M. Aldrich wrote: .. > - Code which, under DOS, requires switches from protected mode to real > mode (some interrupts, BIOS functions, etc.) will run faster under > Linux, because it is a native pm environment; no mode switching is > required. > > - Programs will load faster under Linux because of significantly reduced > overhead to enter protected mode and set up the required DPMI > environment. Linux also features shared libraries, as I understand, so > this may further reduce loading time. > > However, since the time-critical portions of the code are running on the > same CPU and created by essentially the same compiler, there shouldn't > be any noticeable speed difference. > > If anybody knows different, please correct me. :) There IS one caveat: because Linux is a classical multitasking system, each process CAN be suspended for an indefinite amount of time. For example, if it's swapped out. And there isn't a way to "lock" a process in physical memory, so if you're using something like an realtime event handler under Linux (or UNIX generically) you might lose events. There are several ways to fix this: use a realtime UNIX (e.g. LynxOS or QNX); use high-priority/realtime threads (i.e. in Sun Solaris); or use realtime Linux (RTLinux) which features microsecond-level response to system events (at the expense of totally messing up the scheduler for normal-priority programs). ------------------------------------------------------------------- Orlando Alcantara Andico Email: orly AT dilnet DOT upd DOT edu DOT ph ICBM: 14 30 00 N 120 59 00 E POTS: (+632) 932-2385 "If I shed a tear I won't cage it, I won't fear love, and if I feel a rage I won't deny it, I won't fear love." - Sarah Mclachlan