* alloc_pages_exact() triggering memory fragmentation on nommu?
@ 2016-09-01 13:02 Nikita Yushchenko
2016-09-02 10:10 ` Nikita Yushchenko
0 siblings, 1 reply; 2+ messages in thread
From: Nikita Yushchenko @ 2016-09-01 13:02 UTC (permalink / raw)
To: linux-kernel; +Cc: Alexey Maximov
Hi
I'm trying to analyze a system based on NoMMU linux that
badly suffers from memory fragmentation - up to inability
to execute whatever.
Below is a log of /proc/buddyinfo dumped periodically over
system lifetime, that demonstrates how fragmentation progresses.
What catched my eye here is: time to time, something does an
order-7 allocation. But symmetric free almost never happens.
Despite of system being almost idle, no long-running processes
are added, no processes increase in size, only 'ps' and 'cat'
commands to gather logs are periodically executed.
I'm having a guess that this cab be caused by use of
alloc_pages_exact() for NoMMU private anonymous mappings.
This routine causes "tail" of allocation to be returned back
to allocator... and inserted at top of free list. Later, when
whatever in the system makes a trivial order-0 allocation, these
just-freed tails immediately get used (because free pages are
inserted at end of free lists... and new pages are allocated
from either beginning or end of free list, depending on 'cold'
parameter). At a glance, this should have a net effect of much
increased probability of "tail" of large allocation get used
as a small allocation, and thus inability to rebuild a large free
block at time when large allocation is freed.
Is there any protection against this effect in the allocator
of current kernels? (kernel of system in question is somewhat
outdated)
If not, maybe one can be implemented? I.e. by moving "tails" from
alloc_pages_exact() to a different free list to be used only when
no other pages are available?
WBR,
Nikita Yushchenko
Node 0, zone DMA 2 1 6 10 26 54 60 3 1 2 0 2 0 1
Node 0, zone DMA 5 5 6 12 28 56 62 3 0 2 0 2 0 1
Node 0, zone DMA 2 3 6 14 30 59 64 1 1 1 0 2 0 1
Node 0, zone DMA 0 2 8 17 32 61 66 0 0 1 0 2 0 1
Node 0, zone DMA 2 0 8 17 32 61 66 0 0 1 0 2 0 1
Node 0, zone DMA 3 3 7 22 36 66 70 1 0 1 1 1 0 1
Node 0, zone DMA 1 2 7 22 36 66 70 1 0 1 1 1 0 1
Node 0, zone DMA 2 2 8 23 37 67 71 2 1 2 0 1 0 1
Node 0, zone DMA 2 2 8 23 37 67 71 2 1 2 0 1 0 1
Node 0, zone DMA 3 3 9 24 38 68 72 1 1 2 0 1 0 1
Node 0, zone DMA 3 3 9 24 38 68 72 1 1 2 0 1 0 1
Node 0, zone DMA 1 3 9 24 38 68 72 1 1 2 0 1 0 1
Node 0, zone DMA 3 3 10 25 39 69 73 2 0 2 0 1 0 1
Node 0, zone DMA 2 3 10 25 39 69 73 2 0 2 0 1 0 1
Node 0, zone DMA 3 3 11 26 40 70 74 1 0 2 0 1 0 1
Node 0, zone DMA 2 3 11 26 40 70 74 1 0 2 0 1 0 1
Node 0, zone DMA 3 2 11 26 40 70 74 1 0 2 0 1 0 1
Node 0, zone DMA 1 2 11 26 40 70 74 1 0 2 0 1 0 1
Node 0, zone DMA 1 2 11 26 40 70 74 1 0 2 0 1 0 1
Node 0, zone DMA 3 2 12 27 41 71 75 0 0 2 0 1 0 1
Node 0, zone DMA 1 2 12 27 41 71 75 0 0 2 0 1 0 1
Node 0, zone DMA 2 3 11 27 41 71 75 0 0 2 0 1 0 1
Node 0, zone DMA 1 3 11 27 41 71 75 0 0 2 0 1 0 1
Node 0, zone DMA 2 2 11 27 41 71 75 0 0 2 0 1 0 1
Node 0, zone DMA 2 2 12 28 42 72 76 1 1 1 0 1 0 1
Node 0, zone DMA 2 3 14 30 44 74 78 1 0 1 0 1 0 1
Node 0, zone DMA 2 3 13 29 43 73 77 2 0 1 0 1 0 1
Node 0, zone DMA 2 4 14 30 44 74 78 3 1 2 1 0 0 1
Node 0, zone DMA 1 2 13 29 43 73 77 2 0 1 0 1 0 1
Node 0, zone DMA 1 0 15 32 44 74 78 1 1 2 1 0 0 1
Node 0, zone DMA 2 4 14 30 44 74 78 1 0 1 0 1 0 1
Node 0, zone DMA 1 2 15 33 45 75 79 0 1 2 1 0 0 1
Node 0, zone DMA 0 2 15 33 45 75 79 0 1 2 1 0 0 1
Node 0, zone DMA 0 0 15 33 45 75 79 0 1 2 1 0 0 1
Node 0, zone DMA 1 1 16 34 46 76 80 1 0 2 1 0 0 1
Node 0, zone DMA 0 1 16 34 46 76 80 1 0 2 1 0 0 1
Node 0, zone DMA 1 0 16 34 46 76 80 1 0 2 1 0 0 1
Node 0, zone DMA 0 1 17 35 47 77 81 0 0 2 1 0 0 1
Node 0, zone DMA 4 2 15 32 46 76 80 1 1 2 1 0 0 1
Node 0, zone DMA 6 3 14 33 47 77 81 0 1 2 1 0 0 1
Node 0, zone DMA 3 3 14 33 47 77 81 0 1 2 1 0 0 1
Node 0, zone DMA 3 3 14 33 47 77 81 0 1 2 1 0 0 1
Node 0, zone DMA 2 4 15 34 48 78 82 1 0 2 1 0 0 1
Node 0, zone DMA 3 4 15 34 48 78 82 1 0 2 1 0 0 1
Node 0, zone DMA 2 4 15 34 48 78 82 1 0 2 1 0 0 1
Node 0, zone DMA 2 3 15 35 49 79 83 2 1 1 1 0 0 1
Node 0, zone DMA 2 3 15 35 49 79 83 2 1 1 1 0 0 1
Node 0, zone DMA 3 4 15 36 50 80 84 1 1 1 1 0 0 1
Node 0, zone DMA 2 4 14 35 49 79 83 2 1 1 1 0 0 1
Node 0, zone DMA 3 5 15 36 50 80 84 3 0 1 1 0 0 1
Node 0, zone DMA 2 4 15 36 50 80 84 3 0 1 1 0 0 1
Node 0, zone DMA 2 4 15 36 50 80 84 3 0 1 1 0 0 1
Node 0, zone DMA 2 3 15 36 50 80 84 3 0 1 1 0 0 1
Node 0, zone DMA 1 3 15 36 50 80 84 3 0 1 1 0 0 1
Node 0, zone DMA 2 4 16 37 51 81 85 2 0 1 1 0 0 1
Node 0, zone DMA 1 4 16 37 51 81 85 2 0 1 1 0 0 1
Node 0, zone DMA 3 2 16 37 51 81 85 2 0 1 1 0 0 1
Node 0, zone DMA 3 2 16 37 51 81 85 2 0 1 1 0 0 1
Node 0, zone DMA 2 2 16 37 51 81 85 2 0 1 1 0 0 1
Node 0, zone DMA 2 2 16 37 51 81 85 2 0 1 1 0 0 1
Node 0, zone DMA 1 2 16 37 51 81 85 2 0 1 1 0 0 1
Node 0, zone DMA 1 1 16 37 51 81 85 2 0 1 1 0 0 1
Node 0, zone DMA 2 0 16 37 51 81 85 2 0 1 1 0 0 1
Node 0, zone DMA 0 1 17 38 52 82 86 1 0 1 1 0 0 1
Node 0, zone DMA 1 0 17 38 52 82 86 1 0 1 1 0 0 1
Node 0, zone DMA 1 0 17 38 52 82 86 1 0 1 1 0 0 1
Node 0, zone DMA 0 1 18 39 53 83 87 0 0 1 1 0 0 1
Node 0, zone DMA 1 1 18 39 53 83 87 0 0 1 1 0 0 1
Node 0, zone DMA 0 0 21 43 55 85 89 0 0 2 0 0 0 1
Node 0, zone DMA 1 0 22 44 56 86 90 1 1 1 0 0 0 1
Node 0, zone DMA 2 1 23 45 57 87 91 0 1 1 0 0 0 1
Node 0, zone DMA 0 1 23 45 57 87 91 0 1 1 0 0 0 1
Node 0, zone DMA 1 2 22 45 57 87 91 0 1 1 0 0 0 1
Node 0, zone DMA 0 0 21 44 56 86 90 1 1 1 0 0 0 1
Node 0, zone DMA 5 3 22 43 57 87 91 2 1 1 0 0 0 1
Node 0, zone DMA 3 3 22 43 57 87 91 2 1 1 0 0 0 1
Node 0, zone DMA 4 2 22 43 57 87 91 2 1 1 0 0 0 1
Node 0, zone DMA 3 2 22 43 57 87 91 2 1 1 0 0 0 1
Node 0, zone DMA 3 3 23 44 58 88 92 1 1 1 0 0 0 1
Node 0, zone DMA 3 3 23 44 58 88 92 1 1 1 0 0 0 1
Node 0, zone DMA 4 3 22 44 58 88 92 1 1 1 0 0 0 1
Node 0, zone DMA 4 3 22 44 58 88 92 1 1 1 0 0 0 1
Node 0, zone DMA 1 0 24 47 59 89 93 0 0 1 0 0 0 1
Node 0, zone DMA 1 1 25 48 60 90 94 1 1 0 0 0 0 1
Node 0, zone DMA 1 1 25 48 60 90 94 1 1 0 0 0 0 1
Node 0, zone DMA 4 2 23 45 59 89 93 2 0 1 0 0 0 1
Node 0, zone DMA 4 2 23 45 59 89 93 2 0 1 0 0 0 1
Node 0, zone DMA 3 2 23 45 59 89 93 2 0 1 0 0 0 1
Node 0, zone DMA 1 2 23 45 59 89 93 2 0 1 0 0 0 1
Node 0, zone DMA 3 3 25 47 61 91 95 2 1 0 0 0 0 1
Node 0, zone DMA 3 2 25 47 61 91 95 2 1 0 0 0 0 1
Node 0, zone DMA 2 2 25 47 61 91 95 2 1 0 0 0 0 1
Node 0, zone DMA 3 3 26 49 63 93 97 2 0 0 0 0 0 1
Node 0, zone DMA 3 3 26 49 63 93 97 2 0 0 0 0 0 1
Node 0, zone DMA 3 3 26 49 63 93 97 2 0 0 0 0 0 1
Node 0, zone DMA 3 3 26 49 63 93 97 2 0 0 0 0 0 1
Node 0, zone DMA 2 3 26 49 63 93 97 2 0 0 0 0 0 1
Node 0, zone DMA 3 2 26 49 63 93 97 2 0 0 0 0 0 1
Node 0, zone DMA 2 2 26 49 63 93 97 2 0 0 0 0 0 1
Node 0, zone DMA 2 2 27 50 64 94 98 1 0 0 0 0 0 1
Node 0, zone DMA 2 2 27 50 64 94 98 1 0 0 0 0 0 1
Node 0, zone DMA 2 3 28 51 65 95 99 2 1 1 1 1 1 0
Node 0, zone DMA 1 3 28 51 65 95 99 2 1 1 1 1 1 0
Node 0, zone DMA 0 3 28 51 65 95 99 2 1 1 1 1 1 0
Node 0, zone DMA 2 3 29 52 66 96 100 1 1 1 1 1 1 0
Node 0, zone DMA 2 3 29 52 66 96 100 1 1 1 1 1 1 0
Node 0, zone DMA 3 3 30 53 67 97 101 2 0 1 1 1 1 0
Node 0, zone DMA 1 4 33 54 69 99 103 1 0 1 1 1 1 0
Node 0, zone DMA 1 4 35 56 70 100 104 1 1 0 1 1 1 0
Node 0, zone DMA 2 3 35 56 70 100 104 1 1 0 1 1 1 0
Node 0, zone DMA 1 3 35 56 70 100 104 1 1 0 1 1 1 0
Node 0, zone DMA 2 4 36 57 71 101 105 2 0 0 1 1 1 0
Node 0, zone DMA 1 4 36 57 71 101 105 2 0 0 1 1 1 0
Node 0, zone DMA 2 3 36 57 71 101 105 2 0 0 1 1 1 0
Node 0, zone DMA 1 3 36 57 71 101 105 2 0 0 1 1 1 0
Node 0, zone DMA 3 3 36 58 72 102 106 1 0 0 1 1 1 0
Node 0, zone DMA 2 2 37 58 72 102 106 1 0 0 1 1 1 0
Node 0, zone DMA 3 1 38 60 74 104 108 1 1 1 0 1 1 0
Node 0, zone DMA 3 2 38 60 74 104 108 1 1 1 0 1 1 0
Node 0, zone DMA 3 2 38 60 74 104 108 1 1 1 0 1 1 0
Node 0, zone DMA 3 3 40 62 76 106 110 1 0 1 0 1 1 0
Node 0, zone DMA 3 3 39 61 75 105 109 2 0 1 0 1 1 0
Node 0, zone DMA 3 2 38 61 75 105 109 2 0 1 0 1 1 0
Node 0, zone DMA 2 2 39 61 75 105 109 2 0 1 0 1 1 0
Node 0, zone DMA 1 2 39 61 75 105 109 2 0 1 0 1 1 0
Node 0, zone DMA 3 2 40 62 76 106 110 1 0 1 0 1 1 0
Node 0, zone DMA 1 2 40 62 76 106 110 1 0 1 0 1 1 0
Node 0, zone DMA 2 3 38 62 76 106 110 1 0 1 0 1 1 0
Node 0, zone DMA 1 3 39 62 76 106 110 1 0 1 0 1 1 0
Node 0, zone DMA 1 4 40 63 77 107 111 2 1 0 0 1 1 0
Node 0, zone DMA 2 3 40 63 77 107 111 2 1 0 0 1 1 0
Node 0, zone DMA 2 2 40 63 77 107 111 2 1 0 0 1 1 0
Node 0, zone DMA 3 3 41 64 78 108 112 1 1 0 0 1 1 0
Node 0, zone DMA 2 3 41 64 78 108 112 1 1 0 0 1 1 0
Node 0, zone DMA 2 4 42 65 79 109 113 2 0 0 0 1 1 0
Node 0, zone DMA 2 4 42 65 79 109 113 2 0 0 0 1 1 0
Node 0, zone DMA 0 1 44 68 80 110 114 1 1 1 1 0 1 0
Node 0, zone DMA 1 0 44 68 80 110 114 1 1 1 1 0 1 0
Node 0, zone DMA 1 2 45 69 81 111 115 0 1 1 1 0 1 0
Node 0, zone DMA 3 2 44 68 81 111 115 1 1 1 1 0 1 0
Node 0, zone DMA 0 1 45 69 81 111 115 0 1 1 1 0 1 0
Node 0, zone DMA 1 0 45 68 81 111 115 0 1 1 1 0 1 0
Node 0, zone DMA 2 1 44 71 83 113 117 0 0 1 1 0 1 0
Node 0, zone DMA 2 1 46 71 84 114 118 1 1 0 1 0 1 0
Node 0, zone DMA 1 2 45 73 85 115 119 0 1 0 1 0 1 0
Node 0, zone DMA 0 1 45 73 85 115 119 0 1 0 1 0 1 0
Node 0, zone DMA 4 2 43 70 84 114 118 1 0 1 1 0 1 0
Node 0, zone DMA 3 2 43 70 84 114 118 1 0 1 1 0 1 0
Node 0, zone DMA 3 3 44 71 85 115 119 2 1 0 1 0 1 0
Node 0, zone DMA 3 3 44 71 85 115 119 2 1 0 1 0 1 0
Node 0, zone DMA 3 2 44 71 85 115 119 2 1 0 1 0 1 0
Node 0, zone DMA 3 2 44 71 85 115 119 2 1 0 1 0 1 0
Node 0, zone DMA 2 2 44 71 85 115 119 2 1 0 1 0 1 0
Node 0, zone DMA 4 2 45 73 87 117 121 2 0 0 1 0 1 0
Node 0, zone DMA 4 2 45 73 87 117 121 2 0 0 1 0 1 0
Node 0, zone DMA 4 3 46 74 88 118 122 1 0 0 1 0 1 0
Node 0, zone DMA 2 3 46 74 88 118 122 1 0 0 1 0 1 0
Node 0, zone DMA 3 2 46 74 88 118 122 1 0 0 1 0 1 0
Node 0, zone DMA 2 2 46 74 88 118 122 1 0 0 1 0 1 0
Node 0, zone DMA 2 2 46 74 88 118 122 1 0 0 1 0 1 0
Node 0, zone DMA 2 3 47 75 89 119 123 2 1 1 0 0 1 0
Node 0, zone DMA 1 3 47 75 89 119 123 2 1 1 0 0 1 0
Node 0, zone DMA 2 4 48 76 90 120 124 1 1 1 0 0 1 0
Node 0, zone DMA 1 4 48 76 90 120 124 1 1 1 0 0 1 0
Node 0, zone DMA 1 3 49 77 91 121 125 0 1 1 0 0 1 0
Node 0, zone DMA 2 4 50 78 92 122 126 1 2 0 0 0 1 0
Node 0, zone DMA 0 3 49 77 91 121 125 0 1 1 0 0 1 0
Node 0, zone DMA 3 4 49 78 92 122 126 1 0 1 0 0 1 0
Node 0, zone DMA 2 3 50 78 92 122 126 1 0 1 0 0 1 0
Node 0, zone DMA 1 3 50 78 92 122 126 1 0 1 0 0 1 0
Node 0, zone DMA 1 3 50 78 92 122 126 1 0 1 0 0 1 0
Node 0, zone DMA 2 2 50 78 92 122 126 1 0 1 0 0 1 0
Node 0, zone DMA 2 3 51 79 93 123 127 2 1 0 0 0 1 0
Node 0, zone DMA 2 3 51 79 93 123 127 2 1 0 0 0 1 0
Node 0, zone DMA 2 4 52 80 94 124 128 1 1 0 0 0 1 0
Node 0, zone DMA 2 3 52 80 94 124 128 1 1 0 0 0 1 0
Node 0, zone DMA 4 3 53 81 95 125 129 2 0 0 0 0 1 0
Node 0, zone DMA 3 3 53 81 95 125 129 2 0 0 0 0 1 0
Node 0, zone DMA 3 3 53 81 95 125 129 2 0 0 0 0 1 0
Node 0, zone DMA 3 2 53 81 95 125 129 2 0 0 0 0 1 0
Node 0, zone DMA 1 2 53 81 95 125 129 2 0 0 0 0 1 0
Node 0, zone DMA 2 3 54 82 96 126 130 1 0 0 0 0 1 0
Node 0, zone DMA 0 3 54 82 96 126 130 1 0 0 0 0 1 0
Node 0, zone DMA 1 3 55 83 97 127 131 0 0 0 0 0 1 0
Node 0, zone DMA 1 3 55 83 97 127 131 0 0 0 0 0 1 0
Node 0, zone DMA 2 2 55 83 97 127 131 0 0 0 0 0 1 0
Node 0, zone DMA 3 3 56 84 98 128 132 1 1 1 1 1 0 0
Node 0, zone DMA 2 3 56 84 98 128 132 1 1 1 1 1 0 0
Node 0, zone DMA 2 4 57 85 99 129 133 2 0 1 1 1 0 0
Node 0, zone DMA 2 4 57 85 99 129 133 2 0 1 1 1 0 0
Node 0, zone DMA 2 3 57 85 99 129 133 2 0 1 1 1 0 0
Node 0, zone DMA 1 3 57 85 99 129 133 2 0 1 1 1 0 0
Node 0, zone DMA 1 3 57 85 99 129 133 2 0 1 1 1 0 0
Node 0, zone DMA 3 3 58 86 100 130 134 1 0 1 1 1 0 0
Node 0, zone DMA 3 3 58 86 100 130 134 1 0 1 1 1 0 0
Node 0, zone DMA 2 2 58 86 100 130 134 1 0 1 1 1 0 0
Node 0, zone DMA 2 1 58 86 100 130 134 1 0 1 1 1 0 0
Node 0, zone DMA 1 0 61 90 102 132 136 1 0 0 1 1 0 0
Node 0, zone DMA 2 1 62 91 103 133 137 0 0 0 1 1 0 0
Node 0, zone DMA 2 0 62 91 103 133 137 0 0 0 1 1 0 0
Node 0, zone DMA 3 2 61 91 103 133 137 0 0 0 1 1 0 0
Node 0, zone DMA 1 1 59 90 102 132 136 1 0 0 1 1 0 0
Node 0, zone DMA 1 0 61 91 103 133 137 0 0 0 1 1 0 0
Node 0, zone DMA 1 0 63 92 104 134 138 1 1 1 0 1 0 0
Node 0, zone DMA 0 1 64 93 105 135 139 0 1 1 0 1 0 0
Node 0, zone DMA 1 0 64 93 105 135 139 0 1 1 0 1 0 0
Node 0, zone DMA 1 0 64 93 105 135 139 0 1 1 0 1 0 0
Node 0, zone DMA 4 3 63 91 105 135 139 0 0 0 1 1 0 0
Node 0, zone DMA 3 3 63 91 105 135 139 0 0 0 1 1 0 0
Node 0, zone DMA 2 4 64 92 106 136 140 1 1 1 0 1 0 0
Node 0, zone DMA 1 4 64 92 106 136 140 1 1 1 0 1 0 0
Node 0, zone DMA 3 3 64 93 107 137 141 0 1 1 0 1 0 0
Node 0, zone DMA 2 3 64 93 107 137 141 0 1 1 0 1 0 0
Node 0, zone DMA 1 3 64 93 107 137 141 0 1 1 0 1 0 0
Node 0, zone DMA 2 4 65 94 108 138 142 1 0 1 0 1 0 0
Node 0, zone DMA 2 3 65 94 108 138 142 1 0 1 0 1 0 0
Node 0, zone DMA 3 2 65 94 108 138 142 1 0 1 0 1 0 0
Node 0, zone DMA 2 2 65 94 108 138 142 1 0 1 0 1 0 0
Node 0, zone DMA 3 3 66 95 109 139 143 2 1 0 0 1 0 0
Node 0, zone DMA 3 3 66 95 109 139 143 2 1 0 0 1 0 0
Node 0, zone DMA 1 3 66 95 109 139 143 2 1 0 0 1 0 0
Node 0, zone DMA 3 3 67 96 110 140 144 1 1 0 0 1 0 0
Node 0, zone DMA 2 3 67 96 110 140 144 1 1 0 0 1 0 0
Node 0, zone DMA 2 4 69 98 112 142 146 1 0 0 0 1 0 0
Node 0, zone DMA 2 4 68 97 111 141 145 2 0 0 0 1 0 0
Node 0, zone DMA 2 3 68 97 111 141 145 2 0 0 0 1 0 0
Node 0, zone DMA 3 2 68 98 112 142 146 1 0 0 0 1 0 0
Node 0, zone DMA 2 2 68 98 112 142 146 1 0 0 0 1 0 0
Node 0, zone DMA 2 3 70 100 114 144 148 1 1 1 1 0 0 0
Node 0, zone DMA 3 2 69 99 113 143 147 2 1 1 1 0 0 0
Node 0, zone DMA 4 3 70 100 114 144 148 1 1 1 1 0 0 0
Node 0, zone DMA 4 4 71 101 115 145 149 2 2 0 1 0 0 0
Node 0, zone DMA 3 4 71 101 115 145 149 2 2 0 1 0 0 0
Node 0, zone DMA 1 4 71 101 115 145 149 2 2 0 1 0 0 0
Node 0, zone DMA 2 3 71 101 115 145 149 2 2 0 1 0 0 0
Node 0, zone DMA 2 4 72 102 116 146 150 1 2 0 1 0 0 0
Node 0, zone DMA 1 4 73 103 117 147 151 0 2 0 1 0 0 0
Node 0, zone DMA 3 2 72 102 116 146 150 1 2 0 1 0 0 0
Node 0, zone DMA 3 2 73 103 117 147 151 2 1 0 1 0 0 0
Node 0, zone DMA 1 2 72 102 116 146 150 1 2 0 1 0 0 0
Node 0, zone DMA 2 3 73 103 117 147 151 2 1 0 1 0 0 0
Node 0, zone DMA 1 3 73 103 117 147 151 2 1 0 1 0 0 0
Node 0, zone DMA 3 3 74 104 118 148 152 1 1 0 1 0 0 0
Node 0, zone DMA 3 3 74 104 118 148 152 1 1 0 1 0 0 0
Node 0, zone DMA 3 2 74 104 118 148 152 1 1 0 1 0 0 0
Node 0, zone DMA 2 2 74 104 118 148 152 1 1 0 1 0 0 0
Node 0, zone DMA 2 2 74 104 118 148 152 1 1 0 1 0 0 0
Node 0, zone DMA 2 3 75 105 119 149 153 2 0 0 1 0 0 0
Node 0, zone DMA 1 3 76 106 120 150 154 1 0 0 1 0 0 0
Node 0, zone DMA 3 3 76 106 120 150 154 1 0 0 1 0 0 0
Node 0, zone DMA 2 3 76 106 120 150 154 1 0 0 1 0 0 0
Node 0, zone DMA 3 2 76 106 120 150 154 1 0 0 1 0 0 0
Node 0, zone DMA 2 2 76 106 120 150 154 1 0 0 1 0 0 0
Node 0, zone DMA 1 2 76 106 120 150 154 1 0 0 1 0 0 0
Node 0, zone DMA 2 3 77 107 121 151 155 2 1 1 0 0 0 0
Node 0, zone DMA 1 3 77 107 121 151 155 2 1 1 0 0 0 0
Node 0, zone DMA 2 4 78 108 122 152 156 1 1 1 0 0 0 0
Node 0, zone DMA 1 4 78 108 122 152 156 1 1 1 0 0 0 0
Node 0, zone DMA 1 0 80 110 123 153 157 0 0 1 0 0 0 0
Node 0, zone DMA 1 0 80 112 124 154 158 1 1 0 0 0 0 0
Node 0, zone DMA 2 1 81 113 125 155 159 0 1 0 0 0 0 0
Node 0, zone DMA 78 59 129 138 141 157 160 1 0 0 0 0 0 0
Node 0, zone DMA 66 57 126 139 140 156 159 0 1 0 0 0 0 0
Node 0, zone DMA 64 57 126 139 140 156 159 0 1 0 0 0 0 0
Node 0, zone DMA 63 57 126 139 140 156 159 0 1 0 0 0 0 0
Node 0, zone DMA 62 57 126 139 140 156 159 0 1 0 0 0 0 0
Node 0, zone DMA 60 57 124 138 139 155 158 1 1 0 0 0 0 0
Node 0, zone DMA 59 58 124 138 139 155 158 1 1 0 0 0 0 0
Node 0, zone DMA 57 57 125 139 140 156 159 0 1 0 0 0 0 0
Node 0, zone DMA 57 57 126 139 140 156 159 0 1 0 0 0 0 0
Node 0, zone DMA 55 57 126 139 140 156 159 0 1 0 0 0 0 0
Node 0, zone DMA 55 57 124 138 139 155 158 1 1 0 0 0 0 0
Node 0, zone DMA 55 59 124 136 139 155 158 1 0 1 0 0 0 0
Node 0, zone DMA 55 60 124 136 139 155 158 1 0 1 0 0 0 0
Node 0, zone DMA 54 59 124 136 139 155 158 1 0 1 0 0 0 0
Node 0, zone DMA 51 59 124 136 139 155 158 1 0 1 0 0 0 0
Node 0, zone DMA 51 59 124 136 139 155 158 1 0 1 0 0 0 0
Node 0, zone DMA 47 59 124 136 139 155 158 1 0 1 0 0 0 0
Node 0, zone DMA 47 59 124 136 139 155 158 1 0 1 0 0 0 0
Node 0, zone DMA 46 60 124 136 139 155 158 1 0 1 0 0 0 0
Node 0, zone DMA 44 59 124 136 139 155 158 1 0 1 0 0 0 0
Node 0, zone DMA 44 59 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 43 59 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 42 59 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 41 60 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 40 59 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 39 59 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 38 59 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 36 59 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 34 59 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 34 60 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 32 59 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 31 59 124 137 140 156 159 0 0 1 0 0 0 0
Node 0, zone DMA 31 59 125 138 141 157 160 1 1 0 0 0 0 0
Node 0, zone DMA 17 60 125 138 141 157 160 1 1 0 0 0 0 0
Node 0, zone DMA 24 96 127 158 144 160 160 1 0 0 0 0 0 0
Node 0, zone DMA 2 84 128 158 144 160 160 1 0 0 0 0 0 0
Node 0, zone DMA 0 95 128 157 144 158 161 1 0 0 0 0 0 0
Node 0, zone DMA 2 91 128 157 144 158 161 1 0 0 0 0 0 0
Node 0, zone DMA 7 95 128 155 144 158 161 3 0 0 0 0 0 0
Node 0, zone DMA 15 91 129 157 144 158 161 1 0 0 0 0 0 0
Node 0, zone DMA 3 88 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 2 89 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 3 87 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 2 88 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 2 87 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 3 86 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 3 86 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 4 84 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 3 85 128 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 2 84 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 3 83 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 4 82 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 4 81 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 4 81 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 3 80 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 2 80 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 3 79 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 2 79 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 1 79 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 3 77 127 154 143 157 160 2 1 0 0 0 0 0
Node 0, zone DMA 2 78 127 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 6 84 127 156 145 159 162 0 1 0 0 0 0 0
Node 0, zone DMA 22 83 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 4 83 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 3 80 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 1 82 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 2 76 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 2 71 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 4 67 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 4 63 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 3 60 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 17 78 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 20 82 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 1 80 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 29 78 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 0 76 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 1 67 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 9 82 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 2 75 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 1 70 127 156 145 159 162 2 0 0 0 0 0 0
Node 0, zone DMA 0 79 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 1 71 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 3 61 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 2 59 126 155 144 158 161 1 1 0 0 0 0 0
Node 0, zone DMA 7 78 126 156 145 159 162 0 1 0 0 0 0 0
Node 0, zone DMA 1 70 126 156 145 159 162 0 1 0 0 0 0 0
Node 0, zone DMA 13 80 125 155 145 159 162 0 1 0 0 0 0 0
Node 0, zone DMA 1 75 125 155 145 159 162 0 1 0 0 0 0 0
Node 0, zone DMA 2 71 125 155 145 159 162 0 1 0 0 0 0 0
Node 0, zone DMA 15 82 125 155 145 159 162 0 1 0 0 0 0 0
Node 0, zone DMA 2 74 127 156 146 160 163 1 0 0 0 0 0 0
Node 0, zone DMA 1 71 125 156 146 160 163 1 0 0 0 0 0 0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: alloc_pages_exact() triggering memory fragmentation on nommu?
2016-09-01 13:02 alloc_pages_exact() triggering memory fragmentation on nommu? Nikita Yushchenko
@ 2016-09-02 10:10 ` Nikita Yushchenko
0 siblings, 0 replies; 2+ messages in thread
From: Nikita Yushchenko @ 2016-09-02 10:10 UTC (permalink / raw)
To: linux-kernel; +Cc: Alexey Maximov
> I'm having a guess that this can be caused by use of
> alloc_pages_exact() for NoMMU private anonymous mappings.
>
> This routine causes "tail" of allocation to be returned back
> to allocator... and inserted at top of free list. Later, when
> whatever in the system makes a trivial order-0 allocation, these
> just-freed tails immediately get used (because free pages are
> inserted at end of free lists... and new pages are allocated
> from either beginning or end of free list, depending on 'cold'
> parameter). At a glance, this should have a net effect of much
> increased probability of "tail" of large allocation get used
> as a small allocation, and thus inability to rebuild a large free
> block at time when large allocation is freed.
>
> Is there any protection against this effect in the allocator
> of current kernels? (kernel of system in question is somewhat
> outdated)
Just a small followup to whoever may be interested.
The guess was correct.
In old 3.0.8 kernel running on system in question, do_mmap_private() in
mm/nommu.c did not yet use alloc_pages_exact() but instead had it's own
implementation of the same logic. And there was a tunable
'nr_trim_pages' that could alter it. In particular setting that tunable
to 0 effectively disabled any freeing of tails.
We tried to set nr_trim_pages=0 and fragmentation issue went away.
Nikita
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2016-09-01 13:02 alloc_pages_exact() triggering memory fragmentation on nommu? Nikita Yushchenko
2016-09-02 10:10 ` Nikita Yushchenko
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