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From: geert@fozzie.sun3.iaf.nl (Geert Bosch)
Subject: Fast locking (Was Re: Java vs Ada 95)
Date: 1996/11/05
Date: 1996-11-05T00:00:00+00:00	[thread overview]
Message-ID: <55o4g4$ki8@fozzie.sun3.iaf.nl> (raw)
In-Reply-To: dewar.847053681@merv



In article <dewar.847053681@merv> Robert Dewar writes:
   Geert said
   
   "In the more general case a very simple spin-lock is enough and the
    overhead should only be one memory-read when the object is not locked.
    String objects are locked almost never and when they are locked they
    are only locked for a short time."

   What do you mean by a very simple spin lock in a uniprocessor environment.

I meant a lock that uses some form of busy-waiting instead of
blocking. Such a lock can be implemented using atomic test-and-set 
or atomic swap. Although these locks are not efficient for long
waits because of wasted CPU time and possible starving of other
tasks, for resources that are only locked for a short time, like
the ref-counted bounded string example, they are the best solution.

When implementing a sample package for spin locks I found that GNAT
doesn't provide intrinsic subprograms as described in Annex C of the
RM:  "It is recommended that intrinsic subprograms be provided for
convenient access to any machine operations that provide special
capabilities or efficiency that are not otherwise available through the
language constructs." (RM95 C.1(11))

This means that test-and-set is not possible using just GNAT at the
moment and indeed implementing efficient spin-locks is not possible.
Hopefully the extra intrinsic subprograms will be implemented
sometime.

Regards,
   Geert


-- 
E-Mail: geert@sun3.iaf.nl    




  parent reply	other threads:[~1996-11-05  0:00 UTC|newest]

Thread overview: 251+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
1996-10-08  0:00 Once again, Ada absent from DoD SBIR solicitation Gregory Aharonian
1996-10-08  0:00 ` Gandalf
1996-10-09  0:00 ` Bill Nielsen
1996-10-09  0:00   ` Stanley R. Allen
1996-10-09  0:00     ` C++ Standardization (was: Once again, Ada absent from DoD SBIR solicitation) David Shochat
1996-10-10  0:00       ` Robert Dewar
1996-10-10  0:00         ` David Shochat
1996-10-20  0:00           ` Richard Riehle
1996-10-20  0:00             ` nasser
1996-10-21  0:00               ` Shayne Flint
1996-10-21  0:00                 ` Robert A Duff
1996-10-21  0:00                   ` Robert Dewar
1996-10-22  0:00                   ` Ken Garlington
1996-10-22  0:00                   ` Shayne Flint
1996-10-22  0:00                     ` Robert A Duff
1996-10-22  0:00               ` Rush Kester
1996-10-11  0:00         ` Ed Falis
1996-10-11  0:00           ` Robert Dewar
1996-10-12  0:00             ` Kevin D. Heatwole
1996-10-12  0:00               ` Robert Dewar
1996-10-13  0:00                 ` Larry Kilgallen
1996-10-13  0:00             ` Ed Falis
1996-10-11  0:00       ` Dave Wood
1996-10-11  0:00         ` Dave Wood
1996-10-17  0:00         ` Garbage Collection in Ada Thomas Kendelbacher
1996-10-10  0:00     ` Once again, Ada absent from DoD SBIR solicitation Mike Stark
1996-10-10  0:00       ` Stanley R. Allen
1996-10-11  0:00         ` Mitch Gart
1996-10-11  0:00           ` Ken Garlington
1996-10-11  0:00           ` Robert Dewar
1996-10-14  0:00             ` Mitch Gart
1996-10-14  0:00               ` Ken Garlington
1996-10-14  0:00           ` Norman H. Cohen
1996-10-14  0:00             ` Bevin R. Brett
1996-10-10  0:00     ` Mitch Gart
1996-10-10  0:00       ` Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation) Brian Rogoff
1996-10-10  0:00         ` Dave
1996-10-11  0:00           ` Robert Dewar
1996-10-12  0:00             ` davedave
1996-10-12  0:00               ` Robert Dewar
1996-10-13  0:00               ` Larry Kilgallen
1996-10-11  0:00           ` Tucker Taft
1996-10-14  0:00             ` Brian Rogoff
1996-10-15  0:00               ` Mitch Gart
1996-10-15  0:00                 ` Larry Kilgallen
1996-10-15  0:00                   ` Mark A Biggar
1996-10-16  0:00                 ` Brian Rogoff
1996-10-28  0:00                 ` Kenneth Almquist
1996-10-29  0:00                   ` Invoking parental methods (was: Java vs Ada 95) Larry Kilgallen
1996-10-31  0:00                     ` Kenneth Almquist
1996-10-31  0:00                       ` Larry Kilgallen
1996-11-05  0:00                         ` Mitch Gart
1996-11-05  0:00                           ` Tucker Taft
1996-11-05  0:00                             ` Larry Kilgallen
1996-11-06  0:00                               ` Robert A Duff
1996-11-06  0:00                                 ` Larry Kilgallen
1996-11-06  0:00                             ` Robert I. Eachus
1996-11-07  0:00                               ` David Wheeler
1996-11-06  0:00                             ` Mitch Gart
1996-11-08  0:00                             ` Robert I. Eachus
1996-11-08  0:00                             ` Jon S Anthony
1996-11-05  0:00                           ` Larry Kilgallen
1996-11-09  0:00                             ` Joel VanLaven
1996-10-15  0:00               ` Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation) Robert A Duff
1996-10-15  0:00                 ` Portability of Arithmetic (was: Java vs Ada 95) Larry Kilgallen
1996-10-16  0:00                   ` Robert A Duff
1996-10-16  0:00                     ` Robert Dewar
1996-10-17  0:00                       ` Robert A Duff
1996-10-17  0:00                         ` Larry Kilgallen
1996-10-18  0:00                           ` Robert A Duff
1996-10-17  0:00                         ` Robert Dewar
1996-10-18  0:00                           ` Larry Kilgallen
1996-10-18  0:00                             ` Robert A Duff
1996-10-18  0:00                           ` Norman H. Cohen
1996-10-18  0:00                             ` Robert Dewar
1996-10-18  0:00                               ` Brian R. Hanson
1996-10-19  0:00                                 ` Robert Dewar
1996-10-19  0:00                                   ` Larry Kilgallen
1996-10-22  0:00                                     ` Once again, Ada absent from DoD SBIR solicitation Dale Stanbrough
1996-10-27  0:00                                       ` Robert Dewar
1996-10-21  0:00                                   ` Portability of Arithmetic (was: Java vs Ada 95) Norman H. Cohen
1996-10-21  0:00                                     ` Robert Dewar
1996-10-21  0:00                               ` Lance Kibblewhite
1996-10-21  0:00                               ` Norman H. Cohen
1996-10-21  0:00                                 ` Robert Dewar
1996-10-22  0:00                                   ` Larry Kilgallen
1996-10-23  0:00                                     ` Robert Dewar
1996-10-23  0:00                                       ` Larry Kilgallen
1996-10-23  0:00                                   ` Norman H. Cohen
1996-10-17  0:00                     ` Stephen Leake
1996-10-17  0:00                       ` Robert A Duff
1996-10-17  0:00                         ` Robert Dewar
1996-10-17  0:00                         ` Larry Kilgallen
1996-10-18  0:00                           ` Robert A Duff
1996-10-15  0:00                 ` Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation) Robert Dewar
1996-10-17  0:00                 ` Alan Brain
1996-10-17  0:00                   ` Robert Dewar
1996-10-17  0:00                   ` Robert A Duff
1996-10-18  0:00                   ` Keith Thompson
1996-10-20  0:00                     ` Alan Brain
1996-10-24  0:00                 ` Robert I. Eachus
1996-10-15  0:00               ` Mike Stark
1996-10-15  0:00                 ` Robert Dewar
1996-10-16  0:00                   ` Mike Stark
1996-10-17  0:00                     ` Robert A Duff
1996-10-17  0:00                 ` Why no Propagates? Matthew Heaney
1996-10-18  0:00                   ` Robert A Duff
1996-10-18  0:00                   ` Robert Dewar
1996-10-18  0:00                   ` Norman H. Cohen
1996-10-18  0:00                     ` Robert Dewar
1996-10-16  0:00             ` Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation) Brian Rogoff
1996-10-16  0:00             ` Jon S Anthony
1996-10-16  0:00             ` Brian Rogoff
1996-10-16  0:00               ` Robert Dewar
1996-10-17  0:00                 ` Robert A Duff
1996-10-17  0:00                   ` Robert Dewar
1996-11-22  0:00                 ` Van Snyder
1996-11-25  0:00                   ` Java vs Ada vs Inferno, floating point arithmetic Anssi Porttikivi
1996-10-11  0:00           ` Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation) Stephen Leake
1996-10-11  0:00             ` Dave
1996-10-11  0:00               ` Robert Dewar
1996-10-12  0:00                 ` Dave
1996-10-12  0:00                   ` Robert Dewar
1996-10-14  0:00                   ` Keith Thompson
1996-10-18  0:00           ` Why no Propagates? Michel Gauthier
1996-10-22  0:00             ` Richard A. O'Keefe
1996-10-23  0:00           ` Michel Gauthier
1996-10-11  0:00         ` Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation) Mitch Gart
1996-10-11  0:00       ` Jon S Anthony
1996-10-12  0:00         ` Robert Dewar
1996-10-14  0:00           ` Brian R. Hanson
1996-10-14  0:00           ` Mitch Gart
1996-10-14  0:00         ` Keith Thompson
1996-10-15  0:00           ` Dale Stanbrough
1996-10-15  0:00             ` Brian R. Hanson
1996-10-20  0:00           ` nasser
1996-10-11  0:00       ` Jon S Anthony
1996-10-12  0:00       ` davedave
1996-10-12  0:00         ` Robert Dewar
1996-10-16  0:00           ` Jon S Anthony
1996-10-16  0:00           ` Jon S Anthony
1996-10-14  0:00       ` Jon S Anthony
1996-10-14  0:00         ` Robert Dewar
1996-10-15  0:00           ` Robert A Duff
1996-10-15  0:00             ` Larry Kilgallen
1996-10-16  0:00               ` Lars Farm
1996-10-16  0:00                 ` Robert Dewar
1996-10-17  0:00           ` Why no Free? Matthew Heaney
1996-10-18  0:00             ` Robert A Duff
1996-10-18  0:00             ` Robert Dewar
1996-10-18  0:00             ` John Herro
1996-10-19  0:00               ` John Herro
1996-10-14  0:00       ` Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation) Jon S Anthony
1996-10-14  0:00       ` Jon S Anthony
1996-10-14  0:00       ` Jon S Anthony
1996-10-14  0:00       ` Brian Rogoff
1996-10-15  0:00       ` Brian Rogoff
1996-10-15  0:00       ` Robert I. Eachus
1996-10-15  0:00       ` Robert I. Eachus
1996-10-15  0:00         ` Robert Dewar
1996-10-16  0:00       ` Jon S Anthony
1996-10-17  0:00         ` Robert Dewar
1996-10-17  0:00         ` Robert Dewar
1996-10-16  0:00       ` Jon S Anthony
1996-10-18  0:00         ` Keith Thompson
1996-10-16  0:00       ` Samuel T. Harris
1996-10-16  0:00       ` Jon S Anthony
1996-10-16  0:00       ` Jon S Anthony
1996-10-16  0:00       ` Jon S Anthony
1996-10-18  0:00       ` Jon S Anthony
1996-10-18  0:00       ` Jon S Anthony
1996-10-18  0:00       ` Jon S Anthony
1996-10-29  0:00       ` Robert I. Eachus
1996-10-29  0:00       ` Jon S Anthony
1996-10-29  0:00       ` Kenneth Almquist
1996-10-29  0:00         ` Robert Dewar
1996-10-31  0:00           ` Kenneth Almquist
1996-10-30  0:00       ` Stephen Leake
1996-10-31  0:00         ` Lars Farm
1996-10-31  0:00       ` Jon S Anthony
1996-10-31  0:00       ` Kenneth Almquist
1996-11-01  0:00       ` Robert I. Eachus
1996-11-01  0:00         ` Robert A Duff
     [not found]           ` <55gkch$gg6@fozzie.sun3.iaf.nl>
1996-11-03  0:00             ` Robert A Duff
1996-11-03  0:00               ` Robert Dewar
1996-11-04  0:00                 ` Larry Kilgallen
1996-11-04  0:00                   ` Robert Dewar
1996-11-05  0:00                 ` Geert Bosch [this message]
1996-11-06  0:00                   ` Fast locking (Was Re: Java vs Ada 95) Larry Kilgallen
1996-11-06  0:00                     ` Robert Dewar
1996-11-06  0:00                     ` Geert Bosch
1996-11-07  0:00                       ` Larry Kilgallen
1996-11-07  0:00                         ` Robert Dewar
1996-11-11  0:00                           ` Norman H. Cohen
1996-11-08  0:00                         ` Geert Bosch
1996-11-02  0:00         ` Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation) Robert Dewar
1996-11-04  0:00         ` Robert I. Eachus
1996-11-05  0:00           ` Larry Kilgallen
1996-11-14  0:00           ` Robert Dewar
1996-11-16  0:00             ` Geert Bosch
1996-11-17  0:00               ` Robert Dewar
1996-11-17  0:00                 ` Robert A Duff
1996-11-18  0:00                   ` Robert Dewar
1996-11-19  0:00                     ` Robert A Duff
1996-11-18  0:00                 ` Geert Bosch
1996-11-22  0:00                   ` Robert Dewar
1996-11-18  0:00                 ` Norman H. Cohen
1996-11-16  0:00             ` Robert A Duff
1996-11-16  0:00               ` Robert Dewar
1996-11-17  0:00                 ` Unbounded strings (Was: Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation)) Robert A Duff
1996-11-18  0:00                   ` Robert Dewar
1996-11-19  0:00                     ` Robert A Duff
1996-11-23  0:00                       ` Robert Dewar
1996-11-24  0:00                         ` Robert A Duff
1996-11-25  0:00                         ` Norman H. Cohen
1996-11-27  0:00                           ` Robert Dewar
1996-11-19  0:00                     ` Joel VanLaven
1996-11-23  0:00                       ` Robert Dewar
1996-11-21  0:00                   ` Robert I. Eachus
1996-11-24  0:00                     ` Robert Dewar
1996-11-24  0:00                       ` Fergus Henderson
1996-11-24  0:00                         ` Robert Dewar
1996-11-25  0:00                       ` Kevin D. Heatwole
1996-11-25  0:00                         ` Robert A Duff
1996-11-26  0:00                           ` Kevin D. Heatwole
1996-11-26  0:00                             ` Robert A Duff
1996-11-26  0:00                               ` Larry Kilgallen
1996-11-27  0:00                               ` Norman H. Cohen
1996-11-29  0:00                                 ` Fergus Henderson
1996-11-29  0:00                                 ` Robert A Duff
1996-11-27  0:00                               ` Robert Dewar
1996-11-26  0:00                         ` Geert Bosch
1996-11-26  0:00                           ` Robert Dewar
1996-11-25  0:00                   ` Robert I. Eachus
1996-11-20  0:00                 ` Jon S Anthony
1996-11-24  0:00                   ` Robert Dewar
1996-11-06  0:00         ` Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation) Robert I. Eachus
1996-10-11  0:00     ` Ada and the DoD HLA (was: " John Cosby
1996-10-13  0:00     ` Java vs Ada 95 (Was " Hannes Haug
1996-11-03  0:00     ` Hannes Haug
1996-11-06  0:00     ` Fast locking (Was Re: Java vs Ada 95) Hannes Haug
1996-11-06  0:00     ` Hannes Haug
1996-10-11  0:00   ` Once again, Ada absent from DoD SBIR solicitation Matthew M. Lih
1996-10-18  0:00     ` Rush Kester
1996-10-21  0:00   ` C++ Standardization (was: Once again, Ada absent from DoD SBIR solicitation) David Emery
1996-10-10  0:00 ` Jon S Anthony
1996-10-11  0:00 ` Jon S Anthony
1996-10-22  0:00 ` Tarjei Jensen
1996-10-22  0:00   ` C++ Standardization (was: Once again, Ian Ward
1996-11-01  0:00 ` Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation) Jon S Anthony
  -- strict thread matches above, loose matches on Subject: below --
1996-11-12  0:00 Fast locking (Was Re: Java vs Ada 95) Marin David Condic, 561.796.8997, M/S 731-93
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