From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754452AbcHVGR4 (ORCPT ); Mon, 22 Aug 2016 02:17:56 -0400 Received: from mail-wm0-f47.google.com ([74.125.82.47]:35951 "EHLO mail-wm0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750758AbcHVGRz (ORCPT ); Mon, 22 Aug 2016 02:17:55 -0400 Message-ID: <1471846671.4139.50.camel@gmail.com> Subject: why is CONFIG_FRAME_POINTER=y so expensive? From: Mike Galbraith To: LKML Cc: Ingo Molnar Date: Mon, 22 Aug 2016 08:17:51 +0200 Content-Type: text/plain; charset="us-ascii" X-Mailer: Evolution 3.16.5 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Greetings, tbench 8 throughput on my i4790 box: 1 2 3 avg master 3769.95 3759.28 3762.83 3764.02 1.000 master-framepointer 3476.73 3453.52 3460.62 3463.62 .920 Does anyone know why the performance impact is this large? The only thing I found googling was a reference to 3 arg lea using rbp or r13 being slow, which wasn't particularly helpful. Nor was staring at asm deltas with non-expert eyeballs. -Mike