Speeding Up BC & BCC Under Windows

 








  PRODUCT  :  Borland C++                            NUMBER  :  656

  VERSION  :  2.0

       OS  :  PC DOS

     DATE  :  August 12, 1992                          PAGE  :  1/2


    TITLE  :  Speeding Up BC & BCC Under Windows






  Decremental Speed Differential in BC and BCC

  ============================================


  Unfortunately, BC and BCC seem to link more slowly than  their TC

  and TCC counterparts.  Actually, this occurs when linking Windows

  applications,  something that TC and TCC could  not  do  at  all.

  There  are  two  characteristics  of  Windows  applications  that

  combine  to  cause  the  real  mode  linker  to  perform a lot of

  swapping:


     1.  The number of symbols in the Windows import library


     2.  The pattern of references to symbols in the RTL


  In addition,  running under Windows can make things worse because

  EMS is simulated on  disk  by  Windows,  which slows things down.

  When  we  looked  at  tuning  the  linker  to  run faster in this

  specialized situation, any solution we found would have slowed it

  down in every other  situation,  including  running  in protected

  mode.


  The  real mode linker uses EMS or disk for swapping data.  EMS is

  obviously  faster  than   disk;  the  difference  is  accentuated

  especially in the situation  that  happens  to occur when linking

  Windows apps.   Outside of Windows, the linker automatically uses

  EMS if it is available.


  Under Windows, the linker will only have EMS available if the PIF

  makes it available.    Running  a  real mode linker without a PIF

  under Windows  will  be  slow  because  it  will not have any EMS

  available.  Moreover, Windows in enhanced mode uses  a  swap file

  to simulate low, EMS and XMS  memories.    Even if you have a PIF

  which specifies EMS and you are running the linker under enhanced

  mode,  Windows  may  actually be swapping to disk when the linker

  thinks it's using EMS.    This is even less efficient than having

  the linker itself swap to disk, and it gets very slow.


  The  way to prevent Windows from simulating EMS  on  disk  is  by

  specifying EMS memory  as  locked  in  the PIF.  With that setup,

  Windows  will not run the program unless  the  amount  of  memory

  requested is really available.  So the recommended way to run the

  real mode BC or BCC under enhanced mode Windows is to specify one














  PRODUCT  :  Borland C++                            NUMBER  :  656

  VERSION  :  2.0

       OS  :  PC DOS

     DATE  :  August 12, 1992                          PAGE  :  2/2


    TITLE  :  Speeding Up BC & BCC Under Windows





  and a half meg of EMS  in  the  PIF and specify that it's locked.

  More  EMS will probably not make  a  difference  in  performance.

  However, the protected mode  linker--which  does  no  swapping at

  all--will still be faster.


  One final note: BCX  runs  the  protected  mode linker, BCCX does

  not.


  The  long  term  solution is to  provide  DPMI  support  for  our

  protected  mode  tools,  which will allow them to run in enhanced

  mode Windows with all the speed that is now demonstrated  by BCX.

  DPMI support is in the works for our future releases.


  DISCLAIMER: You  have the right to use this technical information

  subject to the terms  of  the  No-Nonsense License Statement that

  you received with  the  Borland product to which this information

  pertains.

































Comments

Post a Comment

Popular posts from this blog

BOTTOM LIVE script

                                  BOTTOM                                   ======                     by Adrian Edmondson and Rik Mayall                                 Bottom Live                                 ===========                               Richie  Rik Mayall                                Eddie  Adrian Edmondson Introduction ------------ [Opening shot of theatre, with huge pictures of Richie and Eddie. Caption: "Live fro...
Read more

Evidence supporting quantum information processing in animals

              Evidence supporting quantum            information processing in animals                    James A. Donald                    1068 Fulton Av                    Sunnyvale, CA 94089-1505                    USA I show that quantum systems can rapidly solve some problems for which finite state machines require a non- polynomially large time. This class of problems is closely related to the class of problems that animals can solve rapidly and effortlessly, but are intractable for computers by all known algorithms. 1. Introduction      Animals, including very simple animals, can rapidly and effortlessly perceive objects, whereas computers take nonpolynomial time to do this by all...
Read more

ARMIES OF CHAOS

                          ARMIES OF CHAOS -      Before anyone proposes more gun control, he or she should know  about a simple, deadly weapon 4 times as powerful as Dirty Harry's  legendary .44 Magnum -- and at least twice as concealable -- that  _can't_ controlled.        This simple, deadly weapon can be made by anyone -- even a  child -- with unpowered hand tools in an hour's time using $5 worth  of materials, most of which are available around the house anyway.   In traditional form it's reusable an unlimited number of times, and  modern plastics have rendered its disposable version electronically  undetectable.  You can clear a room with such a weapon (more of a  hand-held directional grenade than a gun -- sort of a recycleable  Claymore mine) and it's just one of hundreds of similar time-proven  designs. ...
Read more