From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759472AbWLJC3x (ORCPT ); Sat, 9 Dec 2006 21:29:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759616AbWLJC3x (ORCPT ); Sat, 9 Dec 2006 21:29:53 -0500 Received: from web58306.mail.re3.yahoo.com ([68.142.236.159]:21202 "HELO web58306.mail.re3.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1759472AbWLJC3w (ORCPT ); Sat, 9 Dec 2006 21:29:52 -0500 Message-ID: <20061210022951.440.qmail@web58306.mail.re3.yahoo.com> DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:Date:From:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-ID; b=xavpqVQznmSpVeemW0hDBzN5iRoHGwhKjAG24ZsY3w0qp8P+KSdB+Y1hLQC4+W7MF1RllZuKAReqjQiqOHgeKJdK0ElCEg/M/FlhglsPLD3lQwjFmUiWajKZ8YTnVN7jwmt++icsKw3V9MfQNs8AZT3TlJaByK2OOKFe9yDOcd8=; X-YMail-OSG: G8_AtQgVM1lJ2gMq9WXS1qF1FD22QQuE_ywEeXCs_LAkfl7FleXArRm54HPz.lno.A-- Date: Sat, 9 Dec 2006 18:29:51 -0800 (PST) From: xu feng Subject: virtual cache, TLB, and OS To: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, I wish to be personally CC'ed the answers/comments posted to the list in response to this post. I am confused about the following point regarding Virtual Indexed Tag Indexed Cache and i would appreciate any help I have read in this article http://www.linuxjournal.com/article/7105 , the following: << In virtually indexed, virtually tagged (VIVT) caches...suffer from several other problems: 1- Virtual address translations usually are changed as part of normal kernel operation, so the cache must pay careful attention to changes in TLB entries (and changes in address space) and flush cache lines whose translations have changed. 2- Even in a single address space, multiple virtual addresses may exist for the same physical address. Each of these virtual addresses would be cached separately, even though they represent the same data. This is called the cache-line aliasing problem. >> I am just confused about the author: 1- first point, why the cache has to be bothered by the change in the address logical-physical mapping since it is a virtual cache?? 2- could you please give me a situation where two virtual addresses from the same process are mapped to the same physical address? i can't see this happening since each process page is allocated a dedicated frame. sorry if my questions seem obvious thank you for your help ____________________________________________________________________________________ Any questions? Get answers on any topic at www.Answers.yahoo.com. Try it now.