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]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0E56ECAAA1 for ; Thu, 27 Oct 2022 17:30:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 32DAD6B0072; Thu, 27 Oct 2022 13:30:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2DE8C6B0073; Thu, 27 Oct 2022 13:30:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1A5F06B0074; Thu, 27 Oct 2022 13:30:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 0AF136B0072 for ; Thu, 27 Oct 2022 13:30:16 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id C3A31120306 for ; Thu, 27 Oct 2022 17:30:15 +0000 (UTC) X-FDA: 80067417990.28.3BBAE74 Received: from mail-pg1-f176.google.com (mail-pg1-f176.google.com [209.85.215.176]) by imf02.hostedemail.com (Postfix) with ESMTP id 4BDBE8004B for ; Thu, 27 Oct 2022 17:30:15 +0000 (UTC) Received: by mail-pg1-f176.google.com with SMTP id f9so2187819pgj.2 for ; Thu, 27 Oct 2022 10:30:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=i90u/Uf2jYE0+hrCgqCAgN0GAbxmncytTIkPhq3S0qI=; b=EI6URPO1CuEaiVYhCgdKTi96gCaG7jguowcRqg1P4rQc2aXOhQRYoviwLuauhrW/rj IvfRngDCHxTCiVsKVGfU8yxjZxb0ta+useELLhjLfbgD1/HxloRXBMfNVokd2n6b7Sad nEk9LSxHfnHkooXNe2eHo083I7ypbpTaIBbgJ8BoiZhynYGFQMcjo7hFAjToVlD1Rz0D jeVspwwn5FV+spWcYEbo4AMNpX4vAj7y6zldSJY1GKiV+B48TcqBMTwvlTUXnusjvPTu ddhsnX1lhWxk/GmTwLYaWztZ25qT60u4w2PiGxETjmwnTcrao6EmIeN6WKqHhmTsFC2J dH4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=i90u/Uf2jYE0+hrCgqCAgN0GAbxmncytTIkPhq3S0qI=; b=cL+IlkloBaqnf6B/01rCVF6r/WDbNKPF2aW4xkJIHX1pEpa35sg+P7kx2Vb6hKlqxn cSy5h19KmWAmom1MNY5apIKd1Z0YOshox72EOkch9hIf0D/iu1yoQ4vj9uQI8X4nLwi4 PUCCmajjbcyCNkTPsTKSJE4IBb0o2jCxt9aNJeL89OIgsz7qTvTmIkc9sbhgy8+MKz6Y PHR6W/eH4NqtEwMjcSDRu1CwITE0EK48HX+7n0eKwebUluO3rQST4p3QDpH2ieZ1FbTH bHaGXYtxHQvwvndH5+/86zrxnCE34X6SXThS+4l1cGO9Y7ZhJ+2U3B7bk+UtREd8/H+L pGeQ== X-Gm-Message-State: ACrzQf1A885QknBkaZOCvKKr6Dj7ryki8boefRQFiiWNkuCdj4pSBzLU 92nrv32NQnCDSi5lYW6MRK8= X-Google-Smtp-Source: AMsMyM7jC2bcEuLwv2GZWzC1z7PmlNL6h5cLDonNo2ECQ5++cNinRUGeyy5ddU/iI8MIv/Wupb/9cQ== X-Received: by 2002:a65:4508:0:b0:43c:e3c6:d1c2 with SMTP id n8-20020a654508000000b0043ce3c6d1c2mr42555256pgq.582.1666891814045; Thu, 27 Oct 2022 10:30:14 -0700 (PDT) Received: from smtpclient.apple ([66.170.99.95]) by smtp.gmail.com with ESMTPSA id t2-20020aa79462000000b0056c063dd4cfsm1429687pfq.66.2022.10.27.10.30.12 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Oct 2022 10:30:13 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\)) Subject: Re: [PATCH 01/13] mm: Update ptep_get_lockless()s comment From: Nadav Amit In-Reply-To: Date: Thu, 27 Oct 2022 10:30:11 -0700 Cc: Jann Horn , John Hubbard , X86 ML , Matthew Wilcox , Linus Torvalds , Andrew Morton , kernel list , Linux-MM , Andrea Arcangeli , "Kirill A . Shutemov" , jroedel@suse.de, ubizjak@gmail.com Content-Transfer-Encoding: quoted-printable Message-Id: <1701B847-EE00-474A-ACF2-C4051884F8F1@gmail.com> References: <20221022111403.531902164@infradead.org> <20221022114424.515572025@infradead.org> <2c800ed1-d17a-def4-39e1-09281ee78d05@nvidia.com> To: Peter Zijlstra X-Mailer: Apple Mail (2.3696.120.41.1.1) ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=EI6URPO1; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf02.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.215.176 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666891815; a=rsa-sha256; cv=none; b=1PkYsHxOK7kox086sxmuyOP5jqHDpEY4+vcRW9+FrstXN+hm3FK5FQ+kprdLipLFTotAeF urCWNCSOoIdy+hV3nNrEbQ5hO3rNZ83Q0uzxVUDz44DOQ0UyUa3klk3Z8szurc4/uj6T8l LtEl+fkL1Fw4V1yLGBOJSmmqsyUED9s= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666891815; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=i90u/Uf2jYE0+hrCgqCAgN0GAbxmncytTIkPhq3S0qI=; b=VC4yXD8hG+FQLC3jahePs0EX0cDtN/8AF2sg97DXNDvLM9s/A2z9htz7hKM0311utR1s/L 8T4lJTzxm/a/qFt9D/kKMSEjfggNMuo2LZI/oapeQJzsWdyp8LNx7V5/0iju8+P1dkVX70 xTk8/uGDE6pQy9Low64S4JFwsk9b8gk= Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=EI6URPO1; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf02.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.215.176 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com X-Rspam-User: X-Stat-Signature: qhw8e1peomqwdnwmyswweb48y4omwshc X-Rspamd-Queue-Id: 4BDBE8004B X-Rspamd-Server: rspam11 X-HE-Tag: 1666891815-626066 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 Oct 27, 2022, at 12:27 AM, Peter Zijlstra = wrote: >> One alternative may be using mm_tlb_flush_pending() when setting a = new PTE >> to check for pending flushes and flushing the TLB if that is the = case. This >> is somewhat similar to what ptep_clear_flush() does. Anyhow, I guess = this >> might induce some overheads. As noted before, it is possible to track >> pending TLB flushes in VMA/page-table granularity, with different = tradeoffs >> of overheads. >=20 > Right; I just don't believe in VMAs for this, they're *waaay* to big. Well, I did it for VMA in an RFC only because I was pushed. I thought = and do think that page-table granularity is the right one.=