Please help activating NUMA node interleaving for MariaDB.

Using MariaDB 10.1.21 on CentOS Linux release 7.3.1611.

Per instructions on https://mariadb.com/kb/en/mariadb/systemd/ added /etc/systemd/system/mariadb.service.d/custom.conf:

ExecStart=/usr/bin/numactl --interleave=all /usr/sbin/mysqld $MYSQLD_OPTS $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION

/var/log/messages shows that numactl is invoked:

Feb 23 10:40:46 host systemd: Starting MariaDB database server...
Feb 23 10:40:46 host numactl: 2017-02-23 10:40:46 140580844599552 [Note] /usr/sbin/mysqld (mysqld 10.1.21-MariaDB) starting as process 37349 ...
Feb 23 10:40:51 host systemd: Started MariaDB database server.

But numastat shows NUMA node interleaving doesn't work:

[root@host ~]# numastat -p $(pidof mysqld)

Per-node process memory usage (in MBs) for PID 37349 (mysqld)
                           Node 0          Node 1           Total
                  --------------- --------------- ---------------
Huge                         0.00            0.00            0.00
Heap                         0.00            0.00            0.00
Stack                     2711.53         1330.39         4041.92
Private                  23868.98         6126.55        29995.54
----------------  --------------- --------------- ---------------
Total                    26580.51         7456.95        34037.46

As you can see there is a huge imbalance between Node 0 and Node 1.


I'd recommend starting first with checking if that policy had been applied for real. Check out if /proc/…PID-of-interest…/numa_maps has entries denoted as interleave:.

For e. g.:

7ffecdccd000 interleave:0-1 stack anon=8 dirty=8 active=1 N0=4 N1=4 kernelpagesize_kB=4

(I'd assume you won't find such.)

Second thing that I can think of is:

innodb_numa_interleave = on
numa_interleave = on

— At least Percona's scripts are handling the former setting and it can be so that if you haven't explicitly specified them they would be set to default's.

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