Messages in this thread Patch in this message | | | Date | Mon, 10 Jul 2023 17:26:51 +0800 | Subject | Re: [PATCH 2/2] mm: compaction: skip the memory hole rapidly when isolating free pages | From | Baolin Wang <> |
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On 7/10/2023 2:11 PM, Huang, Ying wrote: > Baolin Wang <baolin.wang@linux.alibaba.com> writes: > >> On my machine with below memory layout, and I can see it will take more >> time to skip the larger memory hole (range: 0x100000000 - 0x1800000000) >> when isolating free pages. So adding a new helper to skip the memory >> hole rapidly, which can reduce the time consumed from about 70us to less >> than 1us. >> >> [ 0.000000] Zone ranges: >> [ 0.000000] DMA [mem 0x0000000040000000-0x00000000ffffffff] >> [ 0.000000] DMA32 empty >> [ 0.000000] Normal [mem 0x0000000100000000-0x0000001fa7ffffff] > > The memory hole is at the beginning of zone NORMAL? If so, should zone
No, the memory hole range is 0x1000000000 - 0x1800000000, and the normal zone is start from 0x100000000.
I'm sorry I made a typo in the commit message, which confuses you. The memory hole range should be: 0x1000000000 - 0x1800000000. I updated the commit message to the following and addressed David's comment:
" Just like commit 9721fd82351d ("mm: compaction: skip memory hole rapidly when isolating migratable pages"), I can see it will also take more time to skip the larger memory hole (range: 0x1000000000 - 0x1800000000) when isolating free pages on my machine with below memory layout. So like commit 9721fd82351d, adding a new helper to skip the memory hole rapidly, which can reduce the time consumed from about 70us to less than 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] "
> NORMAL start at 0x1800000000? And, the free pages will not be scanned > there? Or my understanding were wrong. > >> [ 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 <baolin.wang@linux.alibaba.com> >> --- >> mm/compaction.c | 30 +++++++++++++++++++++++++++++- >> 1 file changed, 29 insertions(+), 1 deletion(-) >> >> diff --git a/mm/compaction.c b/mm/compaction.c >> index 43358efdbdc2..9641e2131901 100644 >> --- a/mm/compaction.c >> +++ b/mm/compaction.c >> @@ -249,11 +249,31 @@ static unsigned long skip_offline_sections(unsigned long start_pfn) >> >> return 0; >> } >> + >> +static unsigned long skip_offline_sections_reverse(unsigned long start_pfn) >> +{ >> + unsigned long start_nr = pfn_to_section_nr(start_pfn); >> + >> + if (!start_nr || online_section_nr(start_nr)) >> + return 0; >> + >> + while (start_nr-- > 0) { >> + if (online_section_nr(start_nr)) >> + return section_nr_to_pfn(start_nr) + PAGES_PER_SECTION - 1; >> + } >> + >> + return 0; >> +} >> #else >> static unsigned long skip_offline_sections(unsigned long start_pfn) >> { >> return 0; >> } >> + >> +static unsigned long skip_offline_sections_reverse(unsigned long start_pfn) >> +{ >> + return 0; >> +} >> #endif >> >> /* >> @@ -1668,8 +1688,16 @@ static void isolate_freepages(struct compact_control *cc) >> >> page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn, >> zone); >> - if (!page) >> + if (!page) { >> + unsigned long next_pfn; >> + >> + next_pfn = skip_offline_sections_reverse(block_start_pfn); >> + if (next_pfn) >> + block_start_pfn = max(pageblock_start_pfn(next_pfn), >> + low_pfn); >> + >> continue; >> + } >> >> /* Check the block is suitable for migration */ >> if (!suitable_migration_target(cc, page))
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