From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,3ccb707f4c91a5f2
X-Google-Attributes: gid103376,public
From: kilgallen@eisner.decus.org (Larry Kilgallen)
Subject: Re: Java vs Ada 95 (Was Re: Once again,
 Ada absent from DoD SBIR solicitation)
Date: 1996/11/04
Message-ID: <1996Nov4.072757.1@eisner>#1/1
X-Deja-AN: 194298093
x-nntp-posting-host: eisner.decus.org
references: <325BC3B3.41C6@hso.link.com>
 <EACHUS.96Nov1103759@spectre.mitre.org> <E07Dwq.5L@world.std.com>
 <55gkch$gg6@fozzie.sun3.iaf.nl> <E0B6CL.84r@world.std.com>
 <dewar.847053681@merv>
x-nntp-posting-user: KILGALLEN
x-trace: 847110482/4414
organization: LJK Software
newsgroups: comp.lang.ada
Date: 1996-11-04T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <dewar.847053681@merv>, dewar@merv.cs.nyu.edu (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.

Running under an operating system on a uniprocessor there clearly
must be a method of yielding to the lock-holder.  In a preemptive
scheduling environment this is automatic (although a yielding call
is more polite).  In a non-preemptive scheduling environment,
a simple call to yield the processor should suffice, and that
still leaves the overhead as approximately a memory read and
test.

Larry Kilgallen