From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752811AbeC3VkN (ORCPT ); Fri, 30 Mar 2018 17:40:13 -0400 Received: from mga04.intel.com ([192.55.52.120]:38621 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752665AbeC3VkM (ORCPT ); Fri, 30 Mar 2018 17:40:12 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,383,1517904000"; d="scan'208";a="187411702" Subject: Re: [PATCH 00/11] Use global pages with PTI To: Thomas Gleixner References: <20180323174447.55F35636@viggo.jf.intel.com> <20180327200719.lvdomez6hszpmo4s@gmail.com> <0d6ea030-ec3b-d649-bad7-89ff54094e25@linux.intel.com> <20180330120920.btobga44wqytlkoe@gmail.com> <20180330121725.zcklh36ulg7crydw@gmail.com> <3cdc23a2-99eb-6f93-6934-f7757fa30a3e@linux.intel.com> Cc: Ingo Molnar , Linus Torvalds , Linux Kernel Mailing List , linux-mm , Andrea Arcangeli , Andrew Lutomirski , Kees Cook , Hugh Dickins , =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= , the arch/x86 maintainers , namit@vmware.com From: Dave Hansen Message-ID: <62a0dbae-75eb-6737-6029-4aaf72ebd199@linux.intel.com> Date: Fri, 30 Mar 2018 14:40:11 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/30/2018 01:32 PM, Thomas Gleixner wrote: > On Fri, 30 Mar 2018, Dave Hansen wrote: > >> On 03/30/2018 05:17 AM, Ingo Molnar wrote: >>> BTW., the expectation on !PCID Intel hardware would be for global pages to help >>> even more than the 0.6% and 1.7% you measured on PCID hardware: PCID already >>> _reduces_ the cost of TLB flushes - so if there's not even PCID then global pages >>> should help even more. >>> >>> In theory at least. Would still be nice to measure it. >> >> I did the lseek test on a modern, non-PCID system: >> >> No Global pages (baseline): 6077741 lseeks/sec >> 94 Global pages (this set): 8433111 lseeks/sec >> +2355370 lseeks/sec (+38.8%) > > That's all kernel text, right? What's the result for the case where global > is only set for all user/kernel shared pages? Yes, that's all kernel text (94 global entries). Here's the number with just the entry data/text set global (88 global entries on this system): No Global pages (baseline): 6077741 lseeks/sec 88 Global Pages (kentry ): 7528609 lseeks/sec (+23.9%) 94 Global pages (this set): 8433111 lseeks/sec (+38.8%)