Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751621Ab1DRUQe (ORCPT ); Mon, 18 Apr 2011 16:16:34 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:54084 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751282Ab1DRUQc (ORCPT ); Mon, 18 Apr 2011 16:16:32 -0400 MIME-Version: 1.0 In-Reply-To: References: From: Linus Torvalds Date: Mon, 18 Apr 2011 13:16:11 -0700 Message-ID: Subject: Re: [RFT] Please test rdtsc on various x86-64 hardware (app included) To: Andrew Lutomirski Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andi Kleen , x86 Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1692 Lines: 43 On Mon, Apr 18, 2011 at 12:32 PM, Andrew Lutomirski wrote: > > I've tested on Sandy Bridge, Allendale (i.e. Pentium Dual-Core), > Bloomfield. and C2D. Arrandale: CPU vendor : GenuineIntel CPU model : Intel(R) Core(TM) i5 CPU 670 @ 3.47GHz CPU stepping : 2 TSC flags : tsc rdtscp constant_tsc nonstop_tsc Using lfence_rdtsc because you have an Intel CPU Will test the "lfence;rdtsc" clock. Now test passed : margin 98 with 71696816 samples Load3 test passed: margin 72 with 8926478 samples Load test passed : margin 88 with 14660759 samples Store test failed as expected: worst error 764 with 10784245 samples but that wasn't very surprising since you already tested the micro-architectures just around it. On a dual-socket X5550 (master.kernel.org: 16 threads total: 4 cores per socket, with HT): CPU vendor : GenuineIntel CPU model : Intel(R) Xeon(R) CPU X5550 @ 2.67GHz CPU stepping : 5 TSC flags : tsc rdtscp constant_tsc nonstop_tsc Using lfence_rdtsc because you have an Intel CPU Will test the "lfence;rdtsc" clock. Now test passed : margin 166 with 38875272 samples Load3 test passed: margin 235 with 2972261 samples Load test passed : margin 119 with 4409699 samples Store test failed as expected: worst error 2710 with 3764216 samples Some opteron love would be good, but I don't have access to any right here. Linus -- 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/