From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264057AbTDJOjR (for ); Thu, 10 Apr 2003 10:39:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264058AbTDJOjR (for ); Thu, 10 Apr 2003 10:39:17 -0400 Received: from pixpat.austin.ibm.com ([192.35.232.241]:10959 "EHLO baldur.austin.ibm.com") by vger.kernel.org with ESMTP id S264057AbTDJOjQ (for ); Thu, 10 Apr 2003 10:39:16 -0400 Date: Thu, 10 Apr 2003 09:50:40 -0500 From: Dave McCracken To: "Martin J. Bligh" , Hugh Dickins cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] fix obj vma sorting Message-ID: <21510000.1049986240@baldur.austin.ibm.com> In-Reply-To: <208780000.1049984941@[10.10.2.4]> References: <208780000.1049984941@[10.10.2.4]> X-Mailer: Mulberry/2.2.1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --On Thursday, April 10, 2003 07:29:03 -0700 "Martin J. Bligh" wrote: > Yeah, sorry ... I guess someone should have published the phone > conversation we had yesterday ... > > We came to the conclusion that should be adding the semaphore to the > current code even, as list_add_tail isn't atomic to a doubly linked list > (unless maybe you can do some fancy-pants compare and exchange thing > after setting up the prev pointer of the new element already). Which is > probably going to suck performance-wise, but I'd prefer correctness. From > there we can make a better judgment, but it sounds like it's going to > content horribly on those busy semaphores. I didn't publish the conversation because I realized that the semaphore is taken outside the function, so it is held. It's what I called you back to tell you. I'm guessing the contention we're seeing with Hugh's fix is because of the way ld.so works. It maps the entire library, then does an mprotect to change the idata section from shared to private. It does this for every mapped library after every exec. Dave ====================================================================== Dave McCracken IBM Linux Base Kernel Team 1-512-838-3059 dmccr@us.ibm.com T/L 678-3059