From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752828AbaCAJQ6 (ORCPT ); Sat, 1 Mar 2014 04:16:58 -0500 Received: from mail-ea0-f181.google.com ([209.85.215.181]:44256 "EHLO mail-ea0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750831AbaCAJQz (ORCPT ); Sat, 1 Mar 2014 04:16:55 -0500 Date: Sat, 1 Mar 2014 10:16:50 +0100 From: Ingo Molnar To: Steven Rostedt Cc: Peter Zijlstra , "H. Peter Anvin" , Vince Weaver , Linux Kernel , Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo Subject: Re: perf_fuzzer compiled for x32 causes reboot Message-ID: <20140301091650.GD5885@gmail.com> References: <20140227215726.7018c861@gandalf.local.home> <20140228092341.12a40f7c@gandalf.local.home> <1c583986-74f8-4829-883b-390dc49ddabb@email.android.com> <20140228154026.GH9987@twins.programming.kicks-ass.net> <5310B60F.30806@zytor.com> <20140228112946.1f194397@gandalf.local.home> <20140228205638.GD14089@laptop.programming.kicks-ass.net> <20140228160638.3b045dbc@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140228160638.3b045dbc@gandalf.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Steven Rostedt wrote: > > Also, this function is called a _LOT_ under certain workloads, I > > don't know how cheap a CR2 read is, but it had better be really > > cheap. > > That's a HPA question. We read CR2 in the page fault hot path, so it's on the top of CPU architects' minds and it's reasonably optimized. A couple of cycles IIRC, but would be nice to hear actual numbers. Thanks, Ingo