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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6ADD9CEACF9 for ; Sat, 15 Nov 2025 00:49:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A0A838E001F; Fri, 14 Nov 2025 19:49:22 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9E23E8E0005; Fri, 14 Nov 2025 19:49:22 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 91F618E001F; Fri, 14 Nov 2025 19:49:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 7F90F8E0005 for ; Fri, 14 Nov 2025 19:49:22 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 26D121A05AD for ; Sat, 15 Nov 2025 00:49:22 +0000 (UTC) X-FDA: 84111007764.18.6A4E5A4 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) by imf15.hostedemail.com (Postfix) with ESMTP id 71E6CA0004 for ; Sat, 15 Nov 2025 00:49:19 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b="HFxIY/R6"; spf=pass (imf15.hostedemail.com: domain of ying.huang@linux.alibaba.com designates 115.124.30.132 as permitted sender) smtp.mailfrom=ying.huang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1763167760; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=htUByUHiQNU0PaaZJdOzX/xk7D/ge5gLRVLcI608Ows=; b=YcuzovtfvQOAFiH0TgZxSJhprx7tHh3W5wUZkus/CmQVEJdti9uIAHPuy1JuZulPwSmUlJ ubv5RzpNvmAJpWJ73oCd0lPTEA2+2TT5AFnXpgwL7lZtTr5deeqq0sDsB2BObSjYNo0iDI fQLrLPL3nnizeDu/vNhOxLice50I7Y0= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b="HFxIY/R6"; spf=pass (imf15.hostedemail.com: domain of ying.huang@linux.alibaba.com designates 115.124.30.132 as permitted sender) smtp.mailfrom=ying.huang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1763167760; a=rsa-sha256; cv=none; b=PtE87lyFPd56JELU3IeuVl5RWvTr1qCKoWsG0jxKWfPYweJm/s4T6j8qs2y50i3ferCqM4 ZZECchY2/MLLN07uzg3nk7Ga5Yr51d3CXfbxrmafSlMFZj/ELamG0MPkrbzQUYQQB+ylst jIs65/QHl0jq5sQOog7xosepIB3y15Y= DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1763167756; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; bh=htUByUHiQNU0PaaZJdOzX/xk7D/ge5gLRVLcI608Ows=; b=HFxIY/R6zaU+tEdfztmjxPmjAs/NjtHZmfF8J0i65XeYXWJ6J38OJKOxmyadiZtX/Zjvm3/pDcXrMy853WPt3cQtnrkMIOWF4TODHZu3cJb150x1RaNrxknDOxQvMdB9aL1azHz2C6dp+l811GvhIX7xmaC9/1OBUV9zc8L/u5c= Received: from DESKTOP-5N7EMDA(mailfrom:ying.huang@linux.alibaba.com fp:SMTPD_---0WsOJfMa_1763167753 cluster:ay36) by smtp.aliyun-inc.com; Sat, 15 Nov 2025 08:49:14 +0800 From: "Huang, Ying" To: "David Hildenbrand (Red Hat)" , Catalin Marinas , Will Deacon , Andrew Morton Cc: Ryan Roberts , Barry Song , Zi Yan , Lorenzo Stoakes , Vlastimil Babka , Baolin Wang , Yang Shi , "Christoph Lameter (Ampere)" , Dev Jain , Anshuman Khandual , Kefeng Wang , Kevin Brodsky , Yin Fengwei , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH -v6 2/2] arm64, tlbflush: don't TLBI broadcast if page reused in write fault In-Reply-To: <2bb9f0c2-a258-4a57-882e-9629f9cc81e6@kernel.org> (David Hildenbrand's message of "Fri, 14 Nov 2025 10:49:45 +0100") References: <20251114085403.101552-1-ying.huang@linux.alibaba.com> <20251114085403.101552-3-ying.huang@linux.alibaba.com> <2bb9f0c2-a258-4a57-882e-9629f9cc81e6@kernel.org> Date: Sat, 15 Nov 2025 08:49:12 +0800 Message-ID: <87pl9kf7cn.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 71E6CA0004 X-Stat-Signature: d34rex3p8zqciuaxxm19ctw1esk8zor5 X-Rspam-User: X-HE-Tag: 1763167759-399623 X-HE-Meta: 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 kJQmFgGg 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 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: List-Subscribe: List-Unsubscribe: "David Hildenbrand (Red Hat)" writes: > On 14.11.25 09:54, Huang Ying wrote: >> A multi-thread customer workload with large memory footprint uses >> fork()/exec() to run some external programs every tens seconds. When >> running the workload on an arm64 server machine, it's observed that >> quite some CPU cycles are spent in the TLB flushing functions. While >> running the workload on the x86_64 server machine, it's not. This >> causes the performance on arm64 to be much worse than that on x86_64. >> During the workload running, after fork()/exec() write-protects all >> pages in the parent process, memory writing in the parent process >> will cause a write protection fault. Then the page fault handler >> will make the PTE/PDE writable if the page can be reused, which is >> almost always true in the workload. On arm64, to avoid the write >> protection fault on other CPUs, the page fault handler flushes the TLB >> globally with TLBI broadcast after changing the PTE/PDE. However, this >> isn't always necessary. Firstly, it's safe to leave some stale >> read-only TLB entries as long as they will be flushed finally. >> Secondly, it's quite possible that the original read-only PTE/PDEs >> aren't cached in remote TLB at all if the memory footprint is large. >> In fact, on x86_64, the page fault handler doesn't flush the remote >> TLB in this situation, which benefits the performance a lot. >> To improve the performance on arm64, make the write protection fault >> handler flush the TLB locally instead of globally via TLBI broadcast >> after making the PTE/PDE writable. If there are stale read-only TLB >> entries in the remote CPUs, the page fault handler on these CPUs will >> regard the page fault as spurious and flush the stale TLB entries. >> To test the patchset, make the usemem.c from >> vm-scalability (https://git.kernel.org/pub/scm/linux/kernel/git/wfg/vm-scalability.git). >> support calling fork()/exec() periodically. To mimic the behavior of >> the customer workload, run usemem with 4 threads, access 100GB memory, >> and call fork()/exec() every 40 seconds. Test results show that with >> the patchset the score of usemem improves ~40.6%. The cycles% of TLB >> flush functions reduces from ~50.5% to ~0.3% in perf profile. >> Signed-off-by: Huang Ying >> Reviewed-by: Ryan Roberts >> Reviewed-by: Barry Song >> Acked-by: Zi Yan >> Cc: Catalin Marinas >> Cc: Will Deacon >> Cc: Andrew Morton >> Cc: David Hildenbrand >> Cc: Lorenzo Stoakes >> Cc: Vlastimil Babka >> Cc: Baolin Wang >> Cc: Yang Shi >> Cc: "Christoph Lameter (Ampere)" >> Cc: Dev Jain >> Cc: Anshuman Khandual >> Cc: Kefeng Wang >> Cc: Kevin Brodsky >> Cc: Yin Fengwei >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Cc: linux-mm@kvack.org >> --- > > (no need to resend just for acks/rbs, maintainers can pick that up) Sure. > Reviewed-by: David Hildenbrand (Red Hat) Thank you David! Hi, Maintainers, I have collected some acks/rbs. What do you think about the patchset? What do I need to do for the next step? --- Best Regards, Huang, Ying