From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 References: <155977186863.2443951.9036044808311959913.stgit@dwillia2-desk3.amr.corp.intel.com> <155977188458.2443951.9573565800736334460.stgit@dwillia2-desk3.amr.corp.intel.com> <20190618014223.GD18161@richard> In-Reply-To: <20190618014223.GD18161@richard> From: Dan Williams Date: Tue, 18 Jun 2019 20:40:36 -0700 Message-ID: Subject: Re: [PATCH v9 03/12] mm/hotplug: Prepare shrink_{zone, pgdat}_span for sub-section removal Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org To: Wei Yang Cc: Andrew Morton , Michal Hocko , Pavel Tatashin , linux-nvdimm , Linux Kernel Mailing List , Linux MM , Vlastimil Babka , Oscar Salvador List-ID: On Mon, Jun 17, 2019 at 6:42 PM Wei Yang wrote: > > On Wed, Jun 05, 2019 at 02:58:04PM -0700, Dan Williams wrote: > >Sub-section hotplug support reduces the unit of operation of hotplug > >from section-sized-units (PAGES_PER_SECTION) to sub-section-sized units > >(PAGES_PER_SUBSECTION). Teach shrink_{zone,pgdat}_span() to consider > >PAGES_PER_SUBSECTION boundaries as the points where pfn_valid(), not > >valid_section(), can toggle. > > > >Cc: Michal Hocko > >Cc: Vlastimil Babka > >Cc: Logan Gunthorpe > >Reviewed-by: Pavel Tatashin > >Reviewed-by: Oscar Salvador > >Signed-off-by: Dan Williams > >--- > > mm/memory_hotplug.c | 29 ++++++++--------------------- > > 1 file changed, 8 insertions(+), 21 deletions(-) > > > >diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > >index 7b963c2d3a0d..647859a1d119 100644 > >--- a/mm/memory_hotplug.c > >+++ b/mm/memory_hotplug.c > >@@ -318,12 +318,8 @@ static unsigned long find_smallest_section_pfn(int nid, struct zone *zone, > > unsigned long start_pfn, > > unsigned long end_pfn) > > { > >- struct mem_section *ms; > >- > >- for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SECTION) { > >- ms = __pfn_to_section(start_pfn); > >- > >- if (unlikely(!valid_section(ms))) > >+ for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) { > >+ if (unlikely(!pfn_valid(start_pfn))) > > continue; > > Hmm, we change the granularity of valid section from SECTION to SUBSECTION. > But we didn't change the granularity of node id and zone information. > > For example, we found the node id of a pfn mismatch, we can skip the whole > section instead of a subsection. > > Maybe this is not a big deal. I don't see a problem. 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[209.85.220.65]) by mx.google.com with SMTPS id i7sor8321613oto.26.2019.06.18.20.40.47 for (Google Transport Security); Tue, 18 Jun 2019 20:40:47 -0700 (PDT) Received-SPF: pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@intel-com.20150623.gappssmtp.com header.s=20150623 header.b=BQ7vWgHm; spf=pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=4V43vNNP9UR/YMy0iUrU7kUuUwSqcmG602S5hpOD5NE=; b=BQ7vWgHmVXoWfX5W8xsL12ik15mXugB0SaJil+xQI3I0WxyylMDSZVjeFIBqrMpPVJ Tgiut3d49qvcxdiNlr/Wuqhf5OYmZDTD6pJsL4uc8B7AvZ8wwh8aPM4n71HSolE5Oxc3 FA9Ld6qDcf1gl5dm9y3qsfehBHljHi5HXuDdd7/icxI+t/oHdrlAmeDiUP/Kmr+DiaXd ygMke+1L3EJ6jv6Or7J7ka07JnJyzYJ6usnlq/hrYPaTv2PCenHPThlG9fXMEyQo3ktq qYnDyLZfzEglV0V7mhDK4JYNDdtBeedbRy3nXiodLZw2O63uvgAs/frjTUrFddu2fdwk 1G9Q== X-Google-Smtp-Source: APXvYqzSIN9dPRssFnDKf+ysKlqbDab6DghA3P8E1YBeqgXp36cJF4wdWJZxF+5DmxoFz1Yx1IYT0Jk4KmWR0apXjnU= X-Received: by 2002:a9d:7a9a:: with SMTP id l26mr59223453otn.71.1560915647227; Tue, 18 Jun 2019 20:40:47 -0700 (PDT) MIME-Version: 1.0 References: <155977186863.2443951.9036044808311959913.stgit@dwillia2-desk3.amr.corp.intel.com> <155977188458.2443951.9573565800736334460.stgit@dwillia2-desk3.amr.corp.intel.com> <20190618014223.GD18161@richard> In-Reply-To: <20190618014223.GD18161@richard> From: Dan Williams Date: Tue, 18 Jun 2019 20:40:36 -0700 Message-ID: Subject: Re: [PATCH v9 03/12] mm/hotplug: Prepare shrink_{zone, pgdat}_span for sub-section removal To: Wei Yang Cc: Andrew Morton , Michal Hocko , Pavel Tatashin , linux-nvdimm , Linux Kernel Mailing List , Linux MM , Vlastimil Babka , Oscar Salvador Content-Type: text/plain; charset="UTF-8" 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 Mon, Jun 17, 2019 at 6:42 PM Wei Yang wrote: > > On Wed, Jun 05, 2019 at 02:58:04PM -0700, Dan Williams wrote: > >Sub-section hotplug support reduces the unit of operation of hotplug > >from section-sized-units (PAGES_PER_SECTION) to sub-section-sized units > >(PAGES_PER_SUBSECTION). Teach shrink_{zone,pgdat}_span() to consider > >PAGES_PER_SUBSECTION boundaries as the points where pfn_valid(), not > >valid_section(), can toggle. > > > >Cc: Michal Hocko > >Cc: Vlastimil Babka > >Cc: Logan Gunthorpe > >Reviewed-by: Pavel Tatashin > >Reviewed-by: Oscar Salvador > >Signed-off-by: Dan Williams > >--- > > mm/memory_hotplug.c | 29 ++++++++--------------------- > > 1 file changed, 8 insertions(+), 21 deletions(-) > > > >diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > >index 7b963c2d3a0d..647859a1d119 100644 > >--- a/mm/memory_hotplug.c > >+++ b/mm/memory_hotplug.c > >@@ -318,12 +318,8 @@ static unsigned long find_smallest_section_pfn(int nid, struct zone *zone, > > unsigned long start_pfn, > > unsigned long end_pfn) > > { > >- struct mem_section *ms; > >- > >- for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SECTION) { > >- ms = __pfn_to_section(start_pfn); > >- > >- if (unlikely(!valid_section(ms))) > >+ for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) { > >+ if (unlikely(!pfn_valid(start_pfn))) > > continue; > > Hmm, we change the granularity of valid section from SECTION to SUBSECTION. > But we didn't change the granularity of node id and zone information. > > For example, we found the node id of a pfn mismatch, we can skip the whole > section instead of a subsection. > > Maybe this is not a big deal. I don't see a problem.