From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8E77C43143 for ; Tue, 2 Oct 2018 08:50:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 58D5220878 for ; Tue, 2 Oct 2018 08:50:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="eLEGM5xI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 58D5220878 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727182AbeJBPdG (ORCPT ); Tue, 2 Oct 2018 11:33:06 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:58318 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726734AbeJBPdG (ORCPT ); Tue, 2 Oct 2018 11:33:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2014; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=fSN9y8o955sD9TRd29VV8ptlopxGxFGUqtBgMwhi/20=; b=eLEGM5xISkeufDBnBoKF2ZaQ2 LG5dfwwM7DpBWc+xuaaLdr/eBPWDO013U5bK64kIFDtZ8WGVB8IPFEzV6FzaC5d6L7BxkIrXgIiyP THiH3ulFln/rHlpKGCtkZmzEBK6G87n0IkTso+Cyi/qNoJbYeYBElb+etgDv1Vi5YgBAU=; Received: from n2100.armlinux.org.uk ([2001:4d48:ad52:3201:214:fdff:fe10:4f86]:42632) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.90_1) (envelope-from ) id 1g7GOE-0002fw-Vo; Tue, 02 Oct 2018 09:50:47 +0100 Received: from linux by n2100.armlinux.org.uk with local (Exim 4.90_1) (envelope-from ) id 1g7GOB-0008B7-DN; Tue, 02 Oct 2018 09:50:43 +0100 Date: Tue, 2 Oct 2018 09:50:41 +0100 From: Russell King - ARM Linux To: Mark Salyzyn Cc: John Stultz , lkml , James Morse , Catalin Marinas , Will Deacon , Andy Lutomirski , Dmitry Safonov , Mark Rutland , Laura Abbott , Kees Cook , Ard Biesheuvel , Andy Gross , Kevin Brodsky , Andrew Pinski , Thomas Gleixner , linux-arm-kernel , Jeremy Linton Subject: Re: RESEND and REBASE arm+arm64+aarch32 vdso rewrite Message-ID: <20181002085041.GV30658@n2100.armlinux.org.uk> References: <20181001175845.168430-1-salyzyn@android.com> <8c09a380-7bc8-a353-aeb7-6591e6c57f68@android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8c09a380-7bc8-a353-aeb7-6591e6c57f68@android.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 01, 2018 at 01:44:52PM -0700, Mark Salyzyn wrote: > Despite the gain of 0.4% for screen-on battery life, where Android has a mix > of 64 and 32 bit applications, thus still relevant _today_ on 64 bit > architectures (providing vDSO32 for 32-bit applications). I don't think the issue is what you think it is. 0.4% gain is equivalent to almost (but not quite) 1 minute extra for a lifetime of 4 hours. Is that really noticable, and is it worth the churn from merging this series? Given that the gain is so marginal, I can see why people find it difficult to get excited about this series to spend the time reviewing it. What I'm saying is that the reason that people should look at this series hasn't been "sold" particularly well. How does it look from the system performance point of view - is there a speed-up there that's more significant? In any case, I suspect that if you compare the battery life from kernels from two years ago with modern kernels, you'll see a degredation over that period just because of the progressive increase in complexity, and especially things such as the Spectre work-arounds. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up