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 6D261C433DF for ; Mon, 1 Jun 2020 13:37:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 389FD207BC for ; Mon, 1 Jun 2020 13:37:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 389FD207BC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C36658E0008; Mon, 1 Jun 2020 09:37:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BE5818E0006; Mon, 1 Jun 2020 09:37:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AD72C8E0008; Mon, 1 Jun 2020 09:37:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0101.hostedemail.com [216.40.44.101]) by kanga.kvack.org (Postfix) with ESMTP id 926EE8E0006 for ; Mon, 1 Jun 2020 09:37:06 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 4D9B0180AD806 for ; Mon, 1 Jun 2020 13:37:06 +0000 (UTC) X-FDA: 76880744052.02.day50_5afc12061c641 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id 281C830168 for ; Mon, 1 Jun 2020 13:37:06 +0000 (UTC) X-HE-Tag: day50_5afc12061c641 X-Filterd-Recvd-Size: 5083 Received: from huawei.com (szxga06-in.huawei.com [45.249.212.32]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Mon, 1 Jun 2020 13:37:05 +0000 (UTC) Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 6E5E2EC3AB97623A95A5; Mon, 1 Jun 2020 21:36:50 +0800 (CST) Received: from [127.0.0.1] (10.173.220.25) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.487.0; Mon, 1 Jun 2020 21:36:44 +0800 Subject: Re: [PATCH v2 5/6] mm: tlb: Provide flush_*_tlb_range wrappers To: Catalin Marinas CC: , , , , , , , , , , , , , , , , , , , , , , , , References: <20200423135656.2712-1-yezhenyu2@huawei.com> <20200423135656.2712-6-yezhenyu2@huawei.com> <20200522154254.GD26492@gaia> <20200526145244.GG17051@gaia> <0c6f79e4-f29a-d373-2e43-c4f87cf78b49@huawei.com> <20200601115644.GA23419@gaia> From: Zhenyu Ye Message-ID: Date: Mon, 1 Jun 2020 21:36:41 +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: <20200601115644.GA23419@gaia> Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.173.220.25] X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 281C830168 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2020/6/1 19:56, Catalin Marinas wrote: > Hi Zhenyu, > > On Sat, May 30, 2020 at 06:24:21PM +0800, Zhenyu Ye wrote: >> On 2020/5/26 22:52, Catalin Marinas wrote: >>> On Mon, May 25, 2020 at 03:19:42PM +0800, Zhenyu Ye wrote: >>>> tlb_flush_##_pxx##_range() is used to set tlb->cleared_*, >>>> flush_##_pxx##_tlb_range() will actually flush the TLB entry. >>>> >>>> In arch64, tlb_flush_p?d_range() is defined as: >>>> >>>> #define flush_pmd_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) >>>> #define flush_pud_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) >>> >>> Currently, flush_p??_tlb_range() are generic and defined as above. I >>> think in the generic code they can remain an alias for >>> flush_tlb_range(). >>> >>> On arm64, we can redefine them as: >>> >>> #define flush_pte_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 3) >>> #define flush_pmd_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 2) >>> #define flush_pud_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 1) >>> #define flush_p4d_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 0) >>> >>> (unless the compiler optimises away all the mmu_gather stuff in your >>> macro above but they don't look trivial to me) >> >> I changed generic code before considering that other structures may also >> use this feature, such as Power9. And Peter may want to replace all >> flush_tlb_range() by tlb_flush() in the future, see [1] for details. >> >> If only enable this feature on aarch64, your codes are better. >> >> [1] https://lore.kernel.org/linux-arm-kernel/20200402163849.GM20713@hirez.programming.kicks-ass.net/ > > But we change the semantics slightly if we implement these as > mmu_gather. For example, tlb_end_vma() -> tlb_flush_mmu_tlbonly() ends > up calling mmu_notifier_invalidate_range() which it didn't before. I > think we end up invoking the notifier unnecessarily in some cases (see > the comment in __split_huge_pmd()) or we end up calling the notifier > twice (e.g. pmdp_huge_clear_flush_notify()). > Yes, so only enable this feature on aarch64 may be better. I will change this in V4 of this series. [the v3 only has some minor changes and can be ignored :)] >>> Also, I don't see the new flush_pte_* and flush_p4d_* macros used >>> anywhere and I don't think they are needed. The pte equivalent is >>> flush_tlb_page() (we need to make sure it's not used on a pmd in the >>> hugetlb context). >> >> flush_tlb_page() is used to flush only one page. If we add the >> flush_pte_tlb_range(), then we can use it to flush a range of pages in >> the future. > > If we know flush_tlb_page() is only called on a small page, could we add > TTL information here as well? > Yes, we could. I will add this in flush_tlb_page(). >> But flush_pte_* and flush_p4d_* macros are really not used anywhere. I >> will remove them in next version of series, and add them if someone >> needs. > > I think it makes sense. > Thanks, Zhenyu