Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756694Ab1EPQIM (ORCPT ); Mon, 16 May 2011 12:08:12 -0400 Received: from one.firstfloor.org ([213.235.205.2]:51486 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756547Ab1EPQIL (ORCPT ); Mon, 16 May 2011 12:08:11 -0400 Date: Mon, 16 May 2011 18:08:10 +0200 From: Andi Kleen To: Andy Lutomirski Cc: Andi Kleen , Ingo Molnar , linux-kernel@vger.kernel.org, libc-alpha@sourceware.org, Andi Kleen , Linus Torvalds , Andrew Morton , Thomas Gleixner Subject: Re: [PATCH 4/5] Add a sysconf syscall Message-ID: <20110516160810.GB25898@one.firstfloor.org> References: <1305329059-2017-1-git-send-email-andi@firstfloor.org> <1305329059-2017-5-git-send-email-andi@firstfloor.org> <20110514065752.GA8827@elte.hu> <20110514163424.GU6008@one.firstfloor.org> <4DD14814.8080305@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DD14814.8080305@mit.edu> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 791 Lines: 20 > You could also add a vsyscall function and have that function pull the > values from vvar data. It would be very fast (i.e. almost as fast as > mmaping some data) and it would be more portable. vvar is a global. The variable data in sysconf is per thread (and not even per mm) Even if you ignore the semantic problem of thread versus mm, you would need a new writable page per process and update it any time the rlimits and other information is updated. On the other hand my solution is dead simple and already solves the problem. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/