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 8F4D7C83F22 for ; Fri, 18 Jul 2025 03:21:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 332056B0098; Thu, 17 Jul 2025 23:21:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 30A516B009B; Thu, 17 Jul 2025 23:21:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 246D16B009C; Thu, 17 Jul 2025 23:21:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 17C0F6B0098 for ; Thu, 17 Jul 2025 23:21:52 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 62C96B8317 for ; Fri, 18 Jul 2025 03:21:51 +0000 (UTC) X-FDA: 83675936022.01.BE63ACC Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf15.hostedemail.com (Postfix) with ESMTP id BBBD6A0002 for ; Fri, 18 Jul 2025 03:21:49 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=jlNW1CGI; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1752808909; 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=t9EGkEMqBGQHsTazkl8xjwRGYqUfwg65aaGsxQFsDLg=; b=4qkgypqNWQU4IO+NaGnYXayb2v7kPSAmGKJ9F6HI9qQ2nksgmP6UBELodcj/Wx4gKy5qAW ReQ9oNVh4/c0J5QXp09rqbtl+CINm4sNG2FsXggxOWvpboS4Lfn6+DedV/N6EG6ihzrNvk qyH3DZuAyfnNmaBl0wDNyplT3UZTvOc= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=jlNW1CGI; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1752808909; a=rsa-sha256; cv=none; b=wUEaSGrn0f2TCH29dZf0PQf6vMtvxqAwmnQ6dNbgtddsFL6hTn+/PlsKHmGQJP1wr5ZAgX HEKRHPrllzPJ0/8Vkh+ZCaTaFl1icslt6J+kganwncwrLFiZkrYGgDcfpmQHqvbyZnAys3 2apfr5Z/tCobVEwoWLStTrQsiSRptzw= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id D051D6020B; Fri, 18 Jul 2025 03:21:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AEADC4CEE3; Fri, 18 Jul 2025 03:21:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1752808908; bh=b2fD2BgLJEesI7wAkvlo1CATxqClIgP1m/8XnzokmrE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=jlNW1CGIaibg8DSdi2tsfY+SrzOqS4pUiDUhamKUUFtNSOUILmVESWfDTNGEiEcit jPxHcPHUT96CedlGF/3+jpPVlLbKR7xLPfMgz7Z0JxkTxZ0EvPcb1D1MsF1YihXovC ou/ufVwEmgitX0yudX6RwAqpy8sVaogA2/8KsTVE= Date: Thu, 17 Jul 2025 20:21:46 -0700 From: Andrew Morton To: Ye Liu Cc: David Hildenbrand , Davidlohr Bueso , "Paul E. McKenney" , Josh Triplett , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Boqun Feng , Uladzislau Rezki , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Lorenzo Stoakes , Ye Liu , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Kemeng Shi , Kairui Song , Nhat Pham , Baoquan He , Chris Li , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org Subject: Re: [PATCH] mm: Replace (20 - PAGE_SHIFT) with common macros for pages<->MB conversion Message-Id: <20250717202146.0b9b8f59eae21da8529af559@linux-foundation.org> In-Reply-To: <20250718024134.1304745-1-ye.liu@linux.dev> References: <20250718024134.1304745-1-ye.liu@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: jyjgr8jxps9ebuub1kgy9ek798qegfj3 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: BBBD6A0002 X-Rspam-User: X-HE-Tag: 1752808909-65089 X-HE-Meta: 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 //Nt8L1/ 8U8AfQGNpJlwQYXoTzhUiv+Wm+Tf1L2WdNkHHbe7RHdXL1mKk+eM+Ti5rm5FaFpiOJfBDys49a+Tn5rcY85wT0j3nfgOa0fXgPC00VbmxaOCG4a+9vsPsllaVuUIxhkUS2DAPTrttNMl1+B6iE2hbAFMGKbLY+nSf1XkHFMJ+1yHxTchKUN5nKP6z3PLQEiiDj3hMvmIvQtnhh93btnGZM5T+1l3HGRLUR3oLew1j5Mqsau2BRmDXQ9OEHtBbQf41xDg0scwwuSdiKVgT7ZV4DDb6lX0sLZQxg7xlilZ1wj0MNKajRdsf/G3OKALYNLXbvocj5qFiYpuxGsg2q28XvvWAZzqzkuNV1O/py8pGUNuPlJKSEb+/8fPd4w== 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: On Fri, 18 Jul 2025 10:41:32 +0800 Ye Liu wrote: > From: Ye Liu > > Replace repeated (20 - PAGE_SHIFT) calculations with standard macros: > - MB_TO_PAGES(mb) converts MB to page count > - PAGES_TO_MB(pages) converts pages to MB > > No functional change. > > ... > > +/* > + * Convert between pages and MB > + * 20 is the shift for 1MB (2^20 = 1MB) > + * PAGE_SHIFT is the shift for page size (e.g., 12 for 4KB pages) > + * So (20 - PAGE_SHIFT) converts between pages and MB > + */ > +#define PAGES_TO_MB(pages) ((pages) >> (20 - PAGE_SHIFT)) > +#define MB_TO_PAGES(mb) ((mb) << (20 - PAGE_SHIFT)) > + > #ifdef CONFIG_SYSCTL > extern int sysctl_legacy_va_layout; > #else > > ... > > @@ -796,7 +796,7 @@ kfree_scale_thread(void *arg) > pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n", > (unsigned long long)(end_time - start_time), kfree_loops, > rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started), > - (mem_begin - mem_during) >> (20 - PAGE_SHIFT)); > + PAGES_TO_MB(mem_begin - mem_during)); > > if (shutdown) { > smp_mb(); /* Assign before wake. */ But, but, but, obscure hard-coded magic numbers are there for our job security! Oh well, we got caught. Applied, thanks.