On Wed, Feb 08, 2017 at 11:08:50AM +0100, Michal Hocko wrote:
>On Wed 08-02-17 16:40:55, Gavin Shan wrote:
>> When @node_reclaim_node isn't 0, the page allocator tries to reclaim
>> pages if the amount of free memory in the zones are below the low
>> watermark. On Power platform, none of NUMA nodes are scanned for page
>> reclaim because no nodes match the condition in zone_allows_reclaim().
>> On Power platform, RECLAIM_DISTANCE is set to 10 which is the distance
>> of Node-A to Node-A. So the preferred node even won't be scanned for
>> page reclaim.
>
>This is quite confusing. I can see 56608209d34b ("powerpc/numa: Set a
>smaller value for RECLAIM_DISTANCE to enable zone reclaim") which
>enforced the zone_reclaim by reducing the RECLAIM_DISTANCE, now you are
>building on top of that. Having RECLAIM_DISTANCE == LOCAL_DISTANCE is
>really confusing. What are distances of other nodes (in other words what
>does numactl --hardware tells)?
oops, missed to paste the output from numactl:
# numactl --hardware
available: 2 nodes (0,8)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79
node 0 size: 130703 MB
node 0 free: 127424 MB
node 8 cpus: 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159
node 8 size: 130647 MB
node 8 free: 130038 MB
node distances:
node 0 8
0: 10 40
8: 40 10
Thanks,
Gavin
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html