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 E9684C43334 for ; Wed, 8 Jun 2022 19:50:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5DA7E6B0071; Wed, 8 Jun 2022 15:50:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 589FA6B0072; Wed, 8 Jun 2022 15:50:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4513B6B0073; Wed, 8 Jun 2022 15:50:13 -0400 (EDT) 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 3621C6B0071 for ; Wed, 8 Jun 2022 15:50:13 -0400 (EDT) Received: from smtpin31.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id 011076071C for ; Wed, 8 Jun 2022 19:50:12 +0000 (UTC) X-FDA: 79556109906.31.C88E25A Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf28.hostedemail.com (Postfix) with ESMTP id A3085C0077 for ; Wed, 8 Jun 2022 19:50:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=vB8qr31hPZDrulIC0wNXe3jXMBDgmtAVqOgZUjr6cR0=; b=PoG3IJOzPir+bn8LsRR9955dqy TqBU58ZGvNU8VWRcRDbbb9hPsgfkAW9AO3794kwVAXodLPU9LxjyVGNMXyG35L/z0emBObP1XGz4n CeXLMWRcxZSRFDLDb9+J+2m8qVz1WvZoH5vqrSIowZTpmC8p/sRtpp4Qoc68GjvC+iqDpDWP603na EB0XlwqfSW3nvFhzFLQzPwCQO71cA9s+AdbQdCzD3dg1yqpZmPXMvuLLkrfMKquv2WRyqZK+k8evC Mo64qgsHSGMqpKcpCkdOH7tITcHG2NsUgKkF5Y02vO7nGN9uIc0wwZmPzU5fw0LtK5X7Z+Eui/OT5 4g3Zhp/w==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nz1gj-00CvKE-PH; Wed, 08 Jun 2022 19:49:57 +0000 Date: Wed, 8 Jun 2022 20:49:57 +0100 From: Matthew Wilcox To: Linus Torvalds Cc: Ankur Arora , Linux Kernel Mailing List , Linux-MM , the arch/x86 maintainers , Andrew Morton , Mike Kravetz , Ingo Molnar , Andrew Lutomirski , Thomas Gleixner , Borislav Petkov , Peter Zijlstra , Andi Kleen , Arnd Bergmann , Jason Gunthorpe , jon.grimm@amd.com, Boris Ostrovsky , Konrad Rzeszutek Wilk , Joao Martins Subject: Re: [PATCH v3 00/21] huge page clearing optimizations Message-ID: References: <20220606202109.1306034-1-ankur.a.arora@oracle.com> <87k09s1pgo.fsf@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1654717812; a=rsa-sha256; cv=none; b=HNm1Oqq3nhaENuInKIDW0CJeessimple6TnJWal+WpOvx+gumf5hxcRD49jz+2k6YMxGhp izQNT2I4dtAR1Ib5KmXbQAuiyRiYZf484HfsLdmgG6IELgIfjxci9/B9TDEVCR10gWJuKv ZZWCStmBeN8wPEWByc4t4UJNYxRr4yI= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1654717812; 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=vB8qr31hPZDrulIC0wNXe3jXMBDgmtAVqOgZUjr6cR0=; b=LPES6l2IunfcCPqaXVwUXZBfR3XwoRzaTeHETHWE89jbiloQUCldFKVuDzqoLZ3o/wFGsS k/oGXii4gmqGj4uz2gxcu/wqG9MaclH4rO262ZhtJnijFImlubkWIeCeSzZZUZ+UVVFQI0 mjkmjIwU4XnBRjDUZHdM3EkhyyafHzI= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=PoG3IJOz; dmarc=none; spf=none (imf28.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=PoG3IJOz; dmarc=none; spf=none (imf28.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Stat-Signature: r86s1eh14t7yat9qs8hotf3mo3m9dr37 X-Rspamd-Queue-Id: A3085C0077 X-Rspamd-Server: rspam12 X-Rspam-User: X-HE-Tag: 1654717812-367460 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 Tue, Jun 07, 2022 at 10:56:01AM -0700, Linus Torvalds wrote: > I worry a bit about the insanity of the "gigantic" pages, and the > mem_map_next() games it plays, but that code is from 2008 and I really > doubt it makes any sense to keep around at least for x86. The source > of that abomination is powerpc, and I do not think that whole issue > with MAX_ORDER_NR_PAGES makes any difference on x86, at least. Oh, argh, I meant to delete mem_map_next(), and forgot. If you need to use struct page (a later message hints you don't), just use nth_page() directly. I optimised it so it's not painful except on SPARSEMEM && !SPARSEMEM_VMEMMAP back in December in commit 659508f9c936. And nobody cares about performance on SPARSEMEM && !SPARSEMEM_VMEMMAP systems.