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=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,e81fd3a32a1cacd2 X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news3.google.com!newsfeed2.dallas1.level3.net!newsfeed1.dallas1.level3.net!news.level3.com!wns14feed!worldnet.att.net!attbi_s22.POSTED!53ab2750!not-for-mail From: "Jeffrey R. Carter" User-Agent: Thunderbird 1.5.0.10 (Windows/20070221) MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Arguments for single-mutex-exclusion on protected types (Was: Does Ada tasking profit from multi-core cpus?) References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Message-ID: NNTP-Posting-Host: 12.201.97.213 X-Complaints-To: abuse@mchsi.com X-Trace: attbi_s22 1174153975 12.201.97.213 (Sat, 17 Mar 2007 17:52:55 GMT) NNTP-Posting-Date: Sat, 17 Mar 2007 17:52:55 GMT Organization: AT&T ASP.att.net Date: Sat, 17 Mar 2007 17:52:55 GMT Xref: g2news1.google.com comp.lang.ada:14547 Date: 2007-03-17T17:52:55+00:00 List-Id: Robert A Duff wrote: > > I understand the point about multiprocessor systems, but why do you > say ceiling locking won't work if function calls lock out > other function calls? As I understand ceiling locking (which probably isn't as well as you), its whole point is the absence of any actual lock. The necessary mutual exclusion is achieved through tasks' actual priorities and their positions in the ready-to-run queues when they're preempted. I guess the behavior will be the same with or without the lock. Ceiling locking might be a little faster since it eliminates the overhead of the explicit lock. -- Jeff Carter "My name is Jim, but most people call me ... Jim." Blazing Saddles 39