Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753197Ab1EPRGb (ORCPT ); Mon, 16 May 2011 13:06:31 -0400 Received: from mail-px0-f173.google.com ([209.85.212.173]:62744 "EHLO mail-px0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751968Ab1EPRGa convert rfc822-to-8bit (ORCPT ); Mon, 16 May 2011 13:06:30 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; b=YzfwznWfLyYFRBY3scencVkh6+FwAdl+34i9+HxLLW6R3bHGxlBLH75WbOvWXAbD57 1hY0QfujB+58QDRM8NM/ETCaT5+drvEU9s2gT49JM75hZr07h6w3kA5ykVCydfsDVKul /qHJt60e8cQzgrC5cYRnmlLsXXVwyJc4104gQ= MIME-Version: 1.0 In-Reply-To: <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> <20110516160810.GB25898@one.firstfloor.org> From: Andrew Lutomirski Date: Mon, 16 May 2011 13:06:10 -0400 X-Google-Sender-Auth: KvTTlSmjgu4sOfjzQRvJzqVE6-c Message-ID: Subject: Re: [PATCH 4/5] Add a sysconf syscall To: Andi Kleen Cc: Ingo Molnar , linux-kernel@vger.kernel.org, libc-alpha@sourceware.org, Andi Kleen , Linus Torvalds , Andrew Morton , Thomas Gleixner Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 995 Lines: 28 On Mon, May 16, 2011 at 12:08 PM, Andi Kleen wrote: >> 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. True. I should read the entire list of variables before making suggestions that won't work. :) --Andy > > -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/