Return-Path: Delivered-To: apmail-incubator-harmony-dev-archive@www.apache.org Received: (qmail 27476 invoked from network); 4 Jul 2006 16:06:10 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (209.237.227.199) by minotaur.apache.org with SMTP; 4 Jul 2006 16:06:10 -0000 Received: (qmail 55584 invoked by uid 500); 4 Jul 2006 16:06:08 -0000 Delivered-To: apmail-incubator-harmony-dev-archive@incubator.apache.org Received: (qmail 55232 invoked by uid 500); 4 Jul 2006 16:06:07 -0000 Mailing-List: contact harmony-dev-help@incubator.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: harmony-dev@incubator.apache.org Delivered-To: mailing list harmony-dev@incubator.apache.org Received: (qmail 55220 invoked by uid 99); 4 Jul 2006 16:06:07 -0000 Received: from asf.osuosl.org (HELO asf.osuosl.org) (140.211.166.49) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 04 Jul 2006 09:06:07 -0700 X-ASF-Spam-Status: No, hits=0.5 required=10.0 tests=DNS_FROM_RFC_ABUSE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (asf.osuosl.org: domain of weldonwjw@gmail.com designates 64.233.182.187 as permitted sender) Received: from [64.233.182.187] (HELO nf-out-0910.google.com) (64.233.182.187) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 04 Jul 2006 09:06:06 -0700 Received: by nf-out-0910.google.com with SMTP id p48so553211nfa for ; Tue, 04 Jul 2006 09:05:45 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=nr0mEvtUUosrwCkDPCYWqpNtrXax/gGfvwg9dUYv/eRsTnzYMQReQZ2invZ2FqAh4wSjJtTDK2TLnS5AoCW9JZ4AOPBtvpVDYbRKqKXNtJU262FcWdGZIIKmeb7cGrtQTPPez11M+LCkEe4ufXFioukKUld4DiF+YrCedt4bcpo= Received: by 10.78.177.3 with SMTP id z3mr2769935hue; Tue, 04 Jul 2006 09:05:45 -0700 (PDT) Received: by 10.78.70.8 with HTTP; Tue, 4 Jul 2006 09:05:45 -0700 (PDT) Message-ID: <4dd1f3f00607040905s1844a85ax715a770fb03d64c9@mail.gmail.com> Date: Tue, 4 Jul 2006 09:05:45 -0700 From: "Weldon Washburn" To: harmony-dev@incubator.apache.org Subject: Re: [drlvm/mmtk] jitrino.jet write barrier design questions In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <4dd1f3f00606211606p70d8b05bwa7ebc9e05d396019@mail.gmail.com> <4dd1f3f00606281429x4b132310xd963f0a995ae0443@mail.gmail.com> X-Virus-Checked: Checked by ClamAV on apache.org X-Spam-Rating: minotaur.apache.org 1.6.2 0/1000/N On 6/30/06, Alex Astapchuk wrote: > > Actually, the simplest form of write barrier would be one, single > > parameter -- a ref ptr to the object getting scribbled on. I suspect > > Hmmm... > Seems I have a misunderstanding here - how comes a single ref ? > > What I was thinking of, is that the WB of 2 refs is a kind of > optimization for generational GCs. I recall a thread on this > in harmony-dev - that having an object being written and the > target to write into, such GC can easily detect whether or not > the young 'src' becomes reachable from the old generation. > > But what would be a 'single ref' write barrier intended for ? > Just curious... Good point. I did some digging. The precursor to DRLVM, ORP, has a generational collector with the oldest generation using the train algorithm. The write barrier in ORP has just one argument which is "slot". The comment in ORP code indicates that filtering out uninteresting ref ptrs was tried but showed an overall performance degrade. SableVM has a generational GC that only uses the "slot" pointer. OTOH, MMTk generational collector does filter out uninterresting addresses. It uses both addresses as you suggest above. --------------------------------------------------------------------- Terms of use : http://incubator.apache.org/harmony/mailing.html To unsubscribe, e-mail: harmony-dev-unsubscribe@incubator.apache.org For additional commands, e-mail: harmony-dev-help@incubator.apache.org