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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 5A31FC433DF for ; Mon, 1 Jun 2020 14:57:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2AEBA207FB for ; Mon, 1 Jun 2020 14:57:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727769AbgFAO5u (ORCPT ); Mon, 1 Jun 2020 10:57:50 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:5323 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726067AbgFAO5s (ORCPT ); Mon, 1 Jun 2020 10:57:48 -0400 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 1D32A44F0A1957BAB3EB; Mon, 1 Jun 2020 22:57:46 +0800 (CST) Received: from [127.0.0.1] (10.173.220.25) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.487.0; Mon, 1 Jun 2020 22:57:36 +0800 Subject: Re: [RFC PATCH v3 2/2] arm64: tlb: Use the TLBI RANGE feature in arm64 To: Catalin Marinas CC: , , , , , , , , , , , , , , References: <20200414112835.1121-1-yezhenyu2@huawei.com> <20200414112835.1121-3-yezhenyu2@huawei.com> <20200514152840.GC1907@gaia> <54468aae-dbb1-66bd-c633-82fc75936206@huawei.com> <20200520170759.GE18302@gaia> From: Zhenyu Ye Message-ID: Date: Mon, 1 Jun 2020 22:57:35 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20200520170759.GE18302@gaia> Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.173.220.25] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Catalin, I have sent the v4 of this series [1] and combine the two function with a single loop. See codes for details. [1] https://lore.kernel.org/linux-arm-kernel/20200601144713.2222-1-yezhenyu2@huawei.com/ On 2020/5/21 1:08, Catalin Marinas wrote: >> This optimization is only effective when the range is a multiple of 256KB >> (when the page size is 4KB), and I'm worried about the performance >> of ilog2(). I traced the __flush_tlb_range() last year and found that in >> most cases the range is less than 256K (see details in [1]). > > THP or hugetlbfs would exercise bigger strides but I guess it depends on > the use-case. ilog2() should be reduced to a few instructions on arm64 > AFAICT (haven't tried but it should use the CLZ instruction). > Not bigger than 256K, but the range must be a integer multiple of 256KB, so I still start from scale 0. Thanks, Zhenyu