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 DA708CDB47E for ; Fri, 13 Oct 2023 09:29:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 617F98E0006; Fri, 13 Oct 2023 05:29:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5C80F8D0015; Fri, 13 Oct 2023 05:29:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4B6F68E0006; Fri, 13 Oct 2023 05:29:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 3A0CB8D0015 for ; Fri, 13 Oct 2023 05:29:36 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 0C1B51CA832 for ; Fri, 13 Oct 2023 09:29:36 +0000 (UTC) X-FDA: 81339915552.21.C899AE1 Received: from out-203.mta0.migadu.com (out-203.mta0.migadu.com [91.218.175.203]) by imf24.hostedemail.com (Postfix) with ESMTP id 0E54C18001E for ; Fri, 13 Oct 2023 09:29:33 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=qog+KJ+9; spf=pass (imf24.hostedemail.com: domain of yajun.deng@linux.dev designates 91.218.175.203 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1697189374; 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=v/wjLZqPF3Awyk9wCPsC+oeoryEbbL/rExrT85FbE7g=; b=hbMsUNqxdarMugtgwz1+YZf6660enkXfTRy2T8pWX4IIifIIn0+AeETQLpck1NTDCDD+hE +vm8NYpRhlMmlUwFatVnLB2w4dZQAjyYF5bfsnG2JidqjfP2kpFpvkFq4WOxXIF7t2+nX9 sl9wmD5Yvd5zV1XF6RsS/iwz/Yv8goM= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1697189374; a=rsa-sha256; cv=none; b=1fwn+h3wGIHV+/lfcJTzg0ayNk2qpGsv+DDnTNE1EMnPIeomAnafHITx9R7m6G+2cDUkg+ HNvX3jO0N8N1hv5ArMloxQN8r9NDeHbWs95RWXf/yWpSYT2N/MsO8E+oDo9xcD9BjDxTpp rXOGVWXX5632p7YrpQJUKlkXfGUFxQU= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=qog+KJ+9; spf=pass (imf24.hostedemail.com: domain of yajun.deng@linux.dev designates 91.218.175.203 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev Message-ID: <1c91dd62-886d-bb05-8aee-22191a8a2d8e@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1697189371; h=from:from: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; bh=v/wjLZqPF3Awyk9wCPsC+oeoryEbbL/rExrT85FbE7g=; b=qog+KJ+9Xz9isSq2zUiU+zGAmWX6Vo/7c67KT5LwKYrxehhgfYUCDJcSPv96fSKshioIaB MyF/YdAUO78EQywcEh7HAjhhmOEnmZm1lBjkju83Th/kt7rEwCMwqtb9sUoEb1OifPQraZ 37xNdDoUQ+XL4hpTiOW/+YWyHJFX9Xc= Date: Fri, 13 Oct 2023 17:29:19 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v4 2/2] mm: Init page count in reserve_bootmem_region when MEMINIT_EARLY Content-Language: en-US To: Mike Rapoport Cc: David Hildenbrand , akpm@linux-foundation.org, mike.kravetz@oracle.com, muchun.song@linux.dev, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230928083302.386202-1-yajun.deng@linux.dev> <20230928083302.386202-3-yajun.deng@linux.dev> <20230929083018.GU3303@kernel.org> <2f8c4741-5c7f-272d-9cef-9fda9fbc7ca6@linux.dev> <5382bf2d-5aa0-1498-8169-3248be4b5af3@linux.dev> <38cd0cb9-efe9-b98a-2768-ccb48da8b812@linux.dev> <20231013084827.GT3303@kernel.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yajun Deng In-Reply-To: <20231013084827.GT3303@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 0E54C18001E X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: o9awhayc8estf9sbjp5r9pkba7drz1cz X-HE-Tag: 1697189373-637943 X-HE-Meta: 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 VAAWSiRC J0JPoIQrzKlHIvHw5Xi9Y3LwkyBc2vEvRi6SgqDIEiyMeN1sYC8ulNvmObp6FDmFCt89E54NbpX0ldW2mPhRFYivFtjHAUDmpZ0ujB9hWDkn3QTvbnUzaab9BkSn7mUoAMOwpP1qOCNSmb68klQZZGfQSJEfI4pBrUA+CmfPfc+/6F2afdiD7e391Mw4V+Qo2q5q2 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 2023/10/13 16:48, Mike Rapoport wrote: > On Thu, Oct 12, 2023 at 05:53:22PM +0800, Yajun Deng wrote: >> On 2023/10/12 17:23, David Hildenbrand wrote: >>> On 10.10.23 04:31, Yajun Deng wrote: >>>> On 2023/10/8 16:57, Yajun Deng wrote: >>>>>> That looks wrong. if the page count would by pure luck be 0 >>>>>> already for hotplugged memory, you wouldn't clear the reserved >>>>>> flag. >>>>>> >>>>>> These changes make me a bit nervous. >>>>> Is 'if (page_count(page) || PageReserved(page))' be safer? Or do I >>>>> need to do something else? >>>>> >>>> How about the following if statement? But it needs to add more patch >>>> like v1 ([PATCH 2/4] mm: Introduce MEMINIT_LATE context). >>>> >>>> It'll be safer, but more complex. Please comment... >>>> >>>>     if (context != MEMINIT_EARLY || (page_count(page) || >>>> PageReserved(page)) { >>>> >>> Ideally we could make initialization only depend on the context, and not >>> check for count or the reserved flag. >>> >> This link is v1, >> https://lore.kernel.org/all/20230922070923.355656-1-yajun.deng@linux.dev/ >> >> If we could make initialization only depend on the context, I'll modify it >> based on v1. > Although ~20% improvement looks impressive, this is only optimization of a > fraction of the boot time, and realistically, how much 56 msec saves from > the total boot time when you boot a machine with 190G of RAM? There are a lot of factors that can affect the total boot time. 56 msec saves may be insignificant. But if we look at the boot log, we'll see there's a significant time jump. before: [    0.250334] ACPI: PM-Timer IO Port: 0x508 [    0.618994] Memory: 173413056K/199884452K available (18440K kernel code, 4204K rwdata, 5608K rodata, 3188K init, 17024K bss, 5499616K reserved, 20971520K cma-reserved) after: [    0.260229] software IO TLB: area num 32. [    0.563497] Memory: 173413056K/199884452K available (18440K kernel code, 4204K rwdata, 5608K rodata, 3188K init, 17024K bss, 5499616K reserved, 20971520K cma-reserved) Memory initialization is time consuming in the boot log. > I still think the improvement does not justify the churn, added complexity > and special casing of different code paths of initialization of struct pages. > Because there is a loop, if the order is MAX_ORDER, the loop will run 1024 times. The following 'if' would be safer: 'if (context != MEMINIT_EARLY || (page_count(page) || >> PageReserved(page)) {' This is a foundation. We may change this when we are able to safely remove page init in the hotplug context one day. So the case for the early context is only temporary. >> @Mike,  By the way,  this code will cost more time: >> >>                 if (context == MEMINIT_HOTPLUG) >>                         flags = INIT_PAGE_COUNT | INIT_PAGE_RESERVED; >>                 __init_single_page(page, pfn, zone, nid, flags); >> >> >> [    0.014999] On node 0, zone DMA32: 31679 pages in unavailable ranges >> [    0.311560] ACPI: PM-Timer IO Port: 0x508 >> >> >> This code will cost less time: >> >>                 __init_single_page(page, pfn, zone, nid, 0); >>                 if (context == MEMINIT_HOTPLUG) { >>                         init_page_count(page); >>                         __SetPageReserved(page); >> >> [    0.014299] On node 0, zone DMA32: 31679 pages in unavailable ranges >> [    0.250223] ACPI: PM-Timer IO Port: 0x508 >>