From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753088AbeBOXzr (ORCPT ); Thu, 15 Feb 2018 18:55:47 -0500 Received: from mga05.intel.com ([192.55.52.43]:38177 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752887AbeBOXzq (ORCPT ); Thu, 15 Feb 2018 18:55:46 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,518,1511856000"; d="scan'208";a="175720089" Subject: Re: [PATCH 0/3] Use global pages with PTI To: Linus Torvalds References: <20180215132053.6C9B48C8@viggo.jf.intel.com> Cc: Linux Kernel Mailing List , linux-mm , Andrew Lutomirski , Kees Cook , Hugh Dickins , =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= , the arch/x86 maintainers From: Dave Hansen Message-ID: <91298252-6cef-d4ee-fa77-eb4008eb5f53@linux.intel.com> Date: Thu, 15 Feb 2018 15:55:45 -0800 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 02/15/2018 09:47 AM, Linus Torvalds wrote: > On Thu, Feb 15, 2018 at 5:20 AM, Dave Hansen > wrote: >> During the switch over to PTI, we seem to have lost our ability to have >> GLOBAL mappings. ... > Did you perhaps re-run any benchmark numbers just to verify? Because > it's always good to back up patches that should improve performance > with actual numbers.. Same test as last time except I'm using all 4 cores on a Skylake desktop instead of just 1. The test is this: > https://github.com/antonblanchard/will-it-scale/blob/master/tests/lseek1.c With PCIDs, lseek()s/second go up around 2% to 3% with the these patches enabling the global bit (it's noisy). I measured it at 3% before, so definitely the same ballpark. That was also before all of Andy's trampoline stuff and the syscall fast path removal. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id BE4DE6B0003 for ; Thu, 15 Feb 2018 18:55:47 -0500 (EST) Received: by mail-pg0-f69.google.com with SMTP id h10so833773pgf.3 for ; Thu, 15 Feb 2018 15:55:47 -0800 (PST) Received: from mga07.intel.com (mga07.intel.com. [134.134.136.100]) by mx.google.com with ESMTPS id z11si5685940pgc.464.2018.02.15.15.55.46 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 15 Feb 2018 15:55:46 -0800 (PST) Subject: Re: [PATCH 0/3] Use global pages with PTI References: <20180215132053.6C9B48C8@viggo.jf.intel.com> From: Dave Hansen Message-ID: <91298252-6cef-d4ee-fa77-eb4008eb5f53@linux.intel.com> Date: Thu, 15 Feb 2018 15:55:45 -0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: Linux Kernel Mailing List , linux-mm , Andrew Lutomirski , Kees Cook , Hugh Dickins , =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= , the arch/x86 maintainers On 02/15/2018 09:47 AM, Linus Torvalds wrote: > On Thu, Feb 15, 2018 at 5:20 AM, Dave Hansen > wrote: >> During the switch over to PTI, we seem to have lost our ability to have >> GLOBAL mappings. ... > Did you perhaps re-run any benchmark numbers just to verify? Because > it's always good to back up patches that should improve performance > with actual numbers.. Same test as last time except I'm using all 4 cores on a Skylake desktop instead of just 1. The test is this: > https://github.com/antonblanchard/will-it-scale/blob/master/tests/lseek1.c With PCIDs, lseek()s/second go up around 2% to 3% with the these patches enabling the global bit (it's noisy). I measured it at 3% before, so definitely the same ballpark. That was also before all of Andy's trampoline stuff and the syscall fast path removal. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org