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[2003:cb:c710:ff00:1a06:80f:733a:e8c6]) by smtp.gmail.com with ESMTPSA id 10-20020a05600c24ca00b003f7e4d143cfsm13803139wmu.15.2023.06.13.02.56.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 13 Jun 2023 02:56:03 -0700 (PDT) Message-ID: Date: Tue, 13 Jun 2023 11:56:02 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 To: Baolin Wang , akpm@linux-foundation.org Cc: mgorman@techsingularity.net, vbabka@suse.cz, ying.huang@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <770f9f61472b24b6bc89adbd71a77d9cf62bb54f.1686646361.git.baolin.wang@linux.alibaba.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH v2] mm: compaction: skip memory hole rapidly when isolating migratable pages In-Reply-To: <770f9f61472b24b6bc89adbd71a77d9cf62bb54f.1686646361.git.baolin.wang@linux.alibaba.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: snfom9wcnswwcgc77mfp6sfmwgup73fw X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7CDE680004 X-HE-Tag: 1686650167-509073 X-HE-Meta: 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 Ar/hF3va 306QQkUn0UO2G6Uvma4KO2lAyhLnWT8PdTHxxHJiSYMoTtl6Cuo1vFnlJJHRi4i2nGi/ZDQOy6iaglTtM23AIRkJ11fi6DSDmEu2qXyUeLbSHrHItBOKmXlz/xVogGYfhsBEyM5RqWt71rCX9yGDiv+umkCQkMOLcLh6Q9ReVwmLRe69OAgyhBjqHPkN//mkM9qGxbWqphNgPL71JTpJxbuo0ub4a6jonx4yg8SY1Bh2/SwOaXue7zY5EvQq5E/Brlh/SYMMfMBpMHhdJ4PNQgt3HD3leoWrvmgmjkDxx96AOUqY2LZXQn4fvncLSCpM1uD+6RrM5GOBGpHzkYJ1I10Vhs/S43P+XQndlTuenBQH/5GgAl4QRNI7U7DbhDAJqyXQVoFEWCLaypukpodct3ZZ3mrxETVoPAeK6dGVFaXIfoZmW2zWECO3zBz0XId8JSSRwtseiKIgCi28= 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 13.06.23 10:55, Baolin Wang wrote: > On some machines, the normal zone can have a large memory hole like > below memory layout, and we can see the range from 0x100000000 to > 0x1800000000 is a hole. So when isolating some migratable pages, the > scanner can meet the hole and it will take more time to skip the large > hole. From my measurement, I can see the isolation scanner will take > 80us ~ 100us to skip the large hole [0x100000000 - 0x1800000000]. > > So adding a new helper to fast search next online memory section > to skip the large hole can help to find next suitable pageblock > efficiently. With this patch, I can see the large hole scanning only > takes < 1us. > > [ 0.000000] Zone ranges: > [ 0.000000] DMA [mem 0x0000000040000000-0x00000000ffffffff] > [ 0.000000] DMA32 empty > [ 0.000000] Normal [mem 0x0000000100000000-0x0000001fa7ffffff] > [ 0.000000] Movable zone start for each node > [ 0.000000] Early memory node ranges > [ 0.000000] node 0: [mem 0x0000000040000000-0x0000000fffffffff] > [ 0.000000] node 0: [mem 0x0000001800000000-0x0000001fa3c7ffff] > [ 0.000000] node 0: [mem 0x0000001fa3c80000-0x0000001fa3ffffff] > [ 0.000000] node 0: [mem 0x0000001fa4000000-0x0000001fa402ffff] > [ 0.000000] node 0: [mem 0x0000001fa4030000-0x0000001fa40effff] > [ 0.000000] node 0: [mem 0x0000001fa40f0000-0x0000001fa73cffff] > [ 0.000000] node 0: [mem 0x0000001fa73d0000-0x0000001fa745ffff] > [ 0.000000] node 0: [mem 0x0000001fa7460000-0x0000001fa746ffff] > [ 0.000000] node 0: [mem 0x0000001fa7470000-0x0000001fa758ffff] > [ 0.000000] node 0: [mem 0x0000001fa7590000-0x0000001fa7ffffff] > > Signed-off-by: Baolin Wang > --- > Changes from v1: > - Fix building errors if CONFIG_SPARSEMEM is not selected. > - Use NR_MEM_SECTIONS instead of '-1' per Huang Ying. > --- > include/linux/mmzone.h | 10 ++++++++++ > mm/compaction.c | 30 +++++++++++++++++++++++++++++- > 2 files changed, 39 insertions(+), 1 deletion(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 5a7ada0413da..5ff1fa2efe28 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -2000,6 +2000,16 @@ static inline unsigned long next_present_section_nr(unsigned long section_nr) > return -1; > } > > +static inline unsigned long next_online_section_nr(unsigned long section_nr) > +{ > + while (++section_nr <= __highest_present_section_nr) { > + if (online_section_nr(section_nr)) > + return section_nr; > + } > + > + return NR_MEM_SECTIONS; > +} > + > /* > * These are _only_ used during initialisation, therefore they > * can use __initdata ... They could have names to indicate > diff --git a/mm/compaction.c b/mm/compaction.c > index 3398ef3a55fe..c31ff6123891 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -229,6 +229,28 @@ static void reset_cached_positions(struct zone *zone) > pageblock_start_pfn(zone_end_pfn(zone) - 1); > } > > +#ifdef CONFIG_SPARSEMEM > +static unsigned long skip_hole_pageblock(unsigned long start_pfn) > +{ > + unsigned long next_online_nr; > + unsigned long start_nr = pfn_to_section_nr(start_pfn); > + > + if (online_section_nr(start_nr)) > + return 0; > + > + next_online_nr = next_online_section_nr(start_nr); > + if (next_online_nr < NR_MEM_SECTIONS) > + return section_nr_to_pfn(next_online_nr); > + I would simply inline next_online_section_nr and simplify (and add a comment): /* * If the PFN falls into an offline section, return the start PFN of the * next online section. If the PFN falls into an online section or if * there is no next online section, return 0. */ static unsigned long skip_hole_pageblock(unsigned long start_pfn) { unsigned long nr = pfn_to_section_nr(start_pfn); if (online_section_nr(nr)) return 0; while (++nr <= __highest_present_section_nr) { if (online_section_nr(nr)) return section_nr_to_pfn(nr); } return 0 } Easier, no? And maybe just call that function "skip_offline_sections()" then? Because we're not operating on pageblocks. > + return 0; > +} > +#else > +static unsigned long skip_hole_pageblock(unsigned long start_pfn) > +{ > + return 0; > +} > +#endif > + > /* > * Compound pages of >= pageblock_order should consistently be skipped until > * released. It is always pointless to compact pages of such order (if they are > @@ -1991,8 +2013,14 @@ static isolate_migrate_t isolate_migratepages(struct compact_control *cc) > > page = pageblock_pfn_to_page(block_start_pfn, > block_end_pfn, cc->zone); > - if (!page) > + if (!page) { > + unsigned long next_pfn; > + > + next_pfn = skip_hole_pageblock(block_start_pfn); > + if (next_pfn != 0) if (next_pfn) > + block_end_pfn = next_pfn; > continue; > + } > > /* > * If isolation recently failed, do not retry. Only check the -- Cheers, David / dhildenb