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 51F9BE732D0 for ; Fri, 29 Sep 2023 10:27:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B69258D00D4; Fri, 29 Sep 2023 06:27:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B19168D0023; Fri, 29 Sep 2023 06:27:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A2EE98D00D4; Fri, 29 Sep 2023 06:27:35 -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 94ADE8D0023 for ; Fri, 29 Sep 2023 06:27:35 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 6C06541311 for ; Fri, 29 Sep 2023 10:27:35 +0000 (UTC) X-FDA: 81289258470.15.0496461 Received: from out-207.mta1.migadu.com (out-207.mta1.migadu.com [95.215.58.207]) by imf12.hostedemail.com (Postfix) with ESMTP id 81AE84001A for ; Fri, 29 Sep 2023 10:27:33 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="pB7BXUd/"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf12.hostedemail.com: domain of yajun.deng@linux.dev designates 95.215.58.207 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1695983253; 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=RV4QzVNHVxGJdhZk1D+3xJuIfhjBO2eLrOf32iGE23M=; b=XCbPgUI8JunbAuZbjaEVmv9f+zOOFiIRBvn/qvNv31bTapeQTtqyFLEelG4o6YqJ3Lgt4S PZg7YourYnfyglbNBQzzOXrqhWwwjkmq5xXUMMqomDhCVwvg71Sgu5FstCQqk8PavPs3iu bVQiU/i+M1xrcNo0lOq//MBFnAtr2/Q= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="pB7BXUd/"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf12.hostedemail.com: domain of yajun.deng@linux.dev designates 95.215.58.207 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1695983253; a=rsa-sha256; cv=none; b=BlXq67jjkYpnLXFym6bXmpc+3WtLAJ//UFYCC2WhFHzKU+aY9Uh/5UXg4cv+25ckG5fZlv rvOTCJ9xorYBVCk2kiGAtgPAWCIpYoj57kzftrDpxOUr5hcsgs5H1SjjTF6987RJv9ZIK1 WYILdS/76eMc5sd7w9Kwpkpag1MGhp4= Message-ID: <15233624-f32e-172e-b2f6-7ca7bffbc96d@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1695983251; 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=RV4QzVNHVxGJdhZk1D+3xJuIfhjBO2eLrOf32iGE23M=; b=pB7BXUd/6ZcknJLpvPBQ33+5MVpJVTWoGA3Z+0MoORGPakTH8uGpOoSV7J4zmPUZEGjVru S5izSWOiY8MAIFl/SdvpKTCUMbfSW0BTv8muPSr0oDZ3D67Nuz3QIVYAY2kkZ9b+wuPAz8 8A0umjU9iVCsg8TRfu6M+eM7YknuO+c= Date: Fri, 29 Sep 2023 18:27:25 +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: akpm@linux-foundation.org, mike.kravetz@oracle.com, muchun.song@linux.dev, willy@infradead.org, david@redhat.com, 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> <20230929100252.GW3303@kernel.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yajun Deng In-Reply-To: <20230929100252.GW3303@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 81AE84001A X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: f1jrwa6nnkmwqm14ybbf9ba7ynconymc X-HE-Tag: 1695983253-107267 X-HE-Meta: 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 UHdE9A6N m806iyOclf7dugoqeV18ON3ZmuHV36H13wde1NZw7JgqadKbd+UTxNkCpurikQzId3tbFZUY5/t6vPFK2LxSb+4xSKVVul8X+p12KSQp9YxekNxIEZSGav1usKCqHymc9LEplZqorVSpeU5uNbKikueEYBchZVv+4gW/wxy0KOQxp1bpJg1wSL4Ozt5eYueXj47mU 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 2023/9/29 18:02, Mike Rapoport wrote: > On Fri, Sep 29, 2023 at 05:50:40PM +0800, Yajun Deng wrote: >> On 2023/9/29 16:30, Mike Rapoport wrote: >>> On Thu, Sep 28, 2023 at 04:33:02PM +0800, Yajun Deng wrote: >>>> memmap_init_range() would init page count of all pages, but the free >>>> pages count would be reset in __free_pages_core(). There are opposite >>>> operations. It's unnecessary and time-consuming when it's MEMINIT_EARLY >>>> context. >>>> >>>> Init page count in reserve_bootmem_region when in MEMINIT_EARLY context, >>>> and check the page count before reset it. >>>> >>>> At the same time, the INIT_LIST_HEAD in reserve_bootmem_region isn't >>>> need, as it already done in __init_single_page. >>>> >>>> The following data was tested on an x86 machine with 190GB of RAM. >>>> >>>> before: >>>> free_low_memory_core_early() 341ms >>>> >>>> after: >>>> free_low_memory_core_early() 285ms >>>> >>>> Signed-off-by: Yajun Deng >>>> --- >>>> v4: same with v2. >>>> v3: same with v2. >>>> v2: check page count instead of check context before reset it. >>>> v1: https://lore.kernel.org/all/20230922070923.355656-1-yajun.deng@linux.dev/ >>>> --- >>>> mm/mm_init.c | 18 +++++++++++++----- >>>> mm/page_alloc.c | 20 ++++++++++++-------- >>>> 2 files changed, 25 insertions(+), 13 deletions(-) >>>> >>>> diff --git a/mm/mm_init.c b/mm/mm_init.c >>>> index 9716c8a7ade9..3ab8861e1ef3 100644 >>>> --- a/mm/mm_init.c >>>> +++ b/mm/mm_init.c >>>> @@ -718,7 +718,7 @@ static void __meminit init_reserved_page(unsigned long pfn, int nid) >>>> if (zone_spans_pfn(zone, pfn)) >>>> break; >>>> } >>>> - __init_single_page(pfn_to_page(pfn), pfn, zid, nid, INIT_PAGE_COUNT); >>>> + __init_single_page(pfn_to_page(pfn), pfn, zid, nid, 0); >>>> } >>>> #else >>>> static inline void pgdat_set_deferred_range(pg_data_t *pgdat) {} >>>> @@ -756,8 +756,8 @@ void __meminit reserve_bootmem_region(phys_addr_t start, >>>> init_reserved_page(start_pfn, nid); >>>> - /* Avoid false-positive PageTail() */ >>>> - INIT_LIST_HEAD(&page->lru); >>>> + /* Init page count for reserved region */ >>> Please add a comment that describes _why_ we initialize the page count here. >> Okay. >>>> + init_page_count(page); >>>> /* >>>> * no need for atomic set_bit because the struct >>>> @@ -888,9 +888,17 @@ void __meminit memmap_init_range(unsigned long size, int nid, unsigned long zone >>>> } >>>> page = pfn_to_page(pfn); >>>> - __init_single_page(page, pfn, zone, nid, INIT_PAGE_COUNT); >>>> - if (context == MEMINIT_HOTPLUG) >>>> + >>>> + /* If the context is MEMINIT_EARLY, we will init page count and >>>> + * mark page reserved in reserve_bootmem_region, the free region >>>> + * wouldn't have page count and we will check the pages count >>>> + * in __free_pages_core. >>>> + */ >>>> + __init_single_page(page, pfn, zone, nid, 0); >>>> + if (context == MEMINIT_HOTPLUG) { >>>> + init_page_count(page); >>>> __SetPageReserved(page); >>> Rather than calling init_page_count() and __SetPageReserved() for >>> MEMINIT_HOTPLUG you can set flags to INIT_PAGE_COUNT | INIT_PAGE_RESERVED >>> an call __init_single_page() after the check for MEMINIT_HOTPLUG. >> No, the following code would cost more time than the current code in >> memmap_init(). >> >> if (context == MEMINIT_HOTPLUG) >> >> __init_single_page(page, pfn, zone, nid, INIT_PAGE_COUNT | INIT_PAGE_RESERVED); >> else >> >> __init_single_page(page, pfn, zone, nid, 0); > Sorry if I wasn't clear. What I meant was to have something along these lines: > > enum page_init_flags flags = 0; > > if (context == MEMINIT_HOTPLUG) > flags = INIT_PAGE_COUNT | INIT_PAGE_RESERVED; > __init_single_page(page, pfn, zone, nid, flags); > Okay, I'll test the time consumed in memmap_init(). >>> But more generally, I wonder if we have to differentiate HOTPLUG here at all. >>> @David, can you comment please? >>> >>>> + } >>>> /* >>>> * Usually, we want to mark the pageblock MIGRATE_MOVABLE, >>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >>>> index 06be8821d833..b868caabe8dc 100644 >>>> --- a/mm/page_alloc.c >>>> +++ b/mm/page_alloc.c >>>> @@ -1285,18 +1285,22 @@ void __free_pages_core(struct page *page, unsigned int order) >>>> unsigned int loop; >>>> /* >>>> - * When initializing the memmap, __init_single_page() sets the refcount >>>> - * of all pages to 1 ("allocated"/"not free"). We have to set the >>>> - * refcount of all involved pages to 0. >>>> + * When initializing the memmap, memmap_init_range sets the refcount >>>> + * of all pages to 1 ("reserved" and "free") in hotplug context. We >>>> + * have to set the refcount of all involved pages to 0. Otherwise, >>>> + * we don't do it, as reserve_bootmem_region only set the refcount on >>>> + * reserve region ("reserved") in early context. >>>> */ >>> Again, why hotplug and early init should be different? >> I will add a comment that describes it will save boot time. > But why do we need initialize struct pages differently at boot time vs > memory hotplug? > Is there a reason memory hotplug cannot have page count set to 0 just like > for pages reserved at boot time? > This patch just save boot time in MEMINIT_EARLY. If someone finds out that it can save time in MEMINIT_HOTPLUG, I think it can be done in another patch later. I just keeping it in the same. >>>> - prefetchw(p); >>>> - for (loop = 0; loop < (nr_pages - 1); loop++, p++) { >>>> - prefetchw(p + 1); >>>> + if (page_count(page)) { >>>> + prefetchw(p); >>>> + for (loop = 0; loop < (nr_pages - 1); loop++, p++) { >>>> + prefetchw(p + 1); >>>> + __ClearPageReserved(p); >>>> + set_page_count(p, 0); >>>> + } >>>> __ClearPageReserved(p); >>>> set_page_count(p, 0); >>>> } >>>> - __ClearPageReserved(p); >>>> - set_page_count(p, 0); >>>> atomic_long_add(nr_pages, &page_zone(page)->managed_pages); >>>> -- >>>> 2.25.1 >>>>