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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 666CDC433DB for ; Tue, 23 Feb 2021 06:09:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CCE63601FC for ; Tue, 23 Feb 2021 06:09:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CCE63601FC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4406A6B0006; Tue, 23 Feb 2021 01:09:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3F0236B0070; Tue, 23 Feb 2021 01:09:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 307496B0071; Tue, 23 Feb 2021 01:09:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0061.hostedemail.com [216.40.44.61]) by kanga.kvack.org (Postfix) with ESMTP id 1B5256B0006 for ; Tue, 23 Feb 2021 01:09:55 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 0702918025BF4 for ; Tue, 23 Feb 2021 06:09:54 +0000 (UTC) X-FDA: 77848506708.02.9B7DABE Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf14.hostedemail.com (Postfix) with ESMTP id D9F6EC0001EE for ; Tue, 23 Feb 2021 06:09:46 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 409E7ED1; Mon, 22 Feb 2021 22:09:52 -0800 (PST) Received: from [192.168.0.130] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 368173F73D; Mon, 22 Feb 2021 22:09:47 -0800 (PST) Subject: Re: [PATCH] Documentation/features: mark BATCHED_UNMAP_TLB_FLUSH doesn't apply to ARM64 To: Barry Song , corbet@lwn.net, linux-doc@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linuxarm@openeuler.org, Mel Gorman , Andy Lutomirski , Catalin Marinas , Will Deacon References: <20210223003230.11976-1-song.bao.hua@hisilicon.com> From: Anshuman Khandual Message-ID: <09dd1026-9e3f-b9be-b5a5-82771642348d@arm.com> Date: Tue, 23 Feb 2021 11:40:09 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210223003230.11976-1-song.bao.hua@hisilicon.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Stat-Signature: dignht6ndo69x19rizsn3ptothr46rpz X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D9F6EC0001EE Received-SPF: none (arm.com>: No applicable sender policy available) receiver=imf14; identity=mailfrom; envelope-from=""; helo=foss.arm.com; client-ip=217.140.110.172 X-HE-DKIM-Result: none/none X-HE-Tag: 1614060586-681930 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 2/23/21 6:02 AM, Barry Song wrote: > BATCHED_UNMAP_TLB_FLUSH is used on x86 to do batched tlb shootdown by > sending one IPI to TLB flush all entries after unmapping pages rather > than sending an IPI to flush each individual entry. > On arm64, tlb shootdown is done by hardware. Flush instructions are > innershareable. The local flushes are limited to the boot (1 per CPU) > and when a task is getting a new ASID. Is there any previous discussion around this ? > So marking this feature as "TODO" is not proper. ".." isn't good as > well. So this patch adds a "N/A" for this kind of features which are > not needed on some architectures. > > Cc: Mel Gorman > Cc: Andy Lutomirski > Cc: Catalin Marinas > Cc: Will Deacon > Signed-off-by: Barry Song > --- > Documentation/features/arch-support.txt | 1 + > Documentation/features/vm/TLB/arch-support.txt | 2 +- > 2 files changed, 2 insertions(+), 1 deletion(-) > > diff --git a/Documentation/features/arch-support.txt b/Documentation/features/arch-support.txt > index d22a1095e661..118ae031840b 100644 > --- a/Documentation/features/arch-support.txt > +++ b/Documentation/features/arch-support.txt > @@ -8,4 +8,5 @@ The meaning of entries in the tables is: > | ok | # feature supported by the architecture > |TODO| # feature not yet supported by the architecture > | .. | # feature cannot be supported by the hardware > + | N/A| # feature doesn't apply to the architecture NA might be better here. s/doesn't apply/not applicable/ in order to match NA. Still wondering if NA is really needed when there is already ".." ? Regardless either way should be fine. > > diff --git a/Documentation/features/vm/TLB/arch-support.txt b/Documentation/features/vm/TLB/arch-support.txt > index 30f75a79ce01..0d070f9f98d8 100644 > --- a/Documentation/features/vm/TLB/arch-support.txt > +++ b/Documentation/features/vm/TLB/arch-support.txt > @@ -9,7 +9,7 @@ > | alpha: | TODO | > | arc: | TODO | > | arm: | TODO | > - | arm64: | TODO | > + | arm64: | N/A | > | c6x: | .. | > | csky: | TODO | > | h8300: | .. | >