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,a77baf86c187076a X-Google-Attributes: gid103376,public From: Hans-Juergen Boehm Subject: Re: Garbage collection (was a spinoff of a spinoff of a GA diatribe) Date: 1996/10/25 Message-ID: <32713308.41C6@mti.sgi.com>#1/1 X-Deja-AN: 192057603 references: <9610211427.AA06636@most> <32704FD9.41C6@mti.sgi.com> content-type: text/plain; charset=us-ascii organization: Silicon Graphics Inc., Mountain View, CA mime-version: 1.0 newsgroups: comp.lang.ada x-mailer: Mozilla 2.0S (X11; I; IRIX 6.2 IP22) Date: 1996-10-25T00:00:00+00:00 List-Id: Robert A Duff wrote: > > In article <32704FD9.41C6@mti.sgi.com>, > Hans-Juergen Boehm wrote: > >5. Certain algorithms require SUBSTANTIALLY more locking without GC. > > Could you please give an example of that? > > - Bob Sure. Look at http://reality.sgi.com/employees/boehm_mti/example.html The basic problem is that (frequent)read operations from a (software) cache may need to acquire a lock in order to guard against (infrequent) deallocation by a concurrent cache update. In the GC case the update can atomically replace a pointer and drop the old entry. Reads from the old entry will continue to succeed. -- Hans-Juergen Boehm boehm@mti.sgi.com