From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22A06C43441 for ; Fri, 9 Nov 2018 04:42:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DDA9920855 for ; Fri, 9 Nov 2018 04:42:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DDA9920855 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727567AbeKIOV3 (ORCPT ); Fri, 9 Nov 2018 09:21:29 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:53182 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727473AbeKIOV3 (ORCPT ); Fri, 9 Nov 2018 09:21:29 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6F462EBD; Thu, 8 Nov 2018 20:42:41 -0800 (PST) Received: from [10.162.0.72] (p8cg001049571a15.blr.arm.com [10.162.0.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 290793F5CF; Thu, 8 Nov 2018 20:42:39 -0800 (PST) Subject: Re: arm64 + ARM64_64K_PAGES=y To: Grygorii Strashko , linux-rt-users@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Linux ARM Mailing List References: <1ab7ee03-64fe-384a-c88f-f6d519b965db@ti.com> From: Anshuman Khandual Message-ID: <5d7cde17-67c4-a222-bd66-b0e85a8725fe@arm.com> Date: Fri, 9 Nov 2018 10:12:37 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1ab7ee03-64fe-384a-c88f-f6d519b965db@ti.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/07/2018 03:04 AM, Grygorii Strashko wrote: > Hi All, > > Do anybody tried to use ARM64 RT with 76K pages enabled? > > My attempt shows that enabling  CONFIG_ARM64_64K_PAGES=y increases latencies by ~30% Depends on what the workload is actually doing. 64K pages should help if the mapping is multiple of 64K, persistent and accesses patterns are more or less linear to be nice with the TLB. 64K can take bit more time if the memory requirement is way smaller than 64K in which case latency probably can increase just to zero out the single page allocated. Latency can add up if this happens on a regular basis. perf report can help find out more on this.