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NUMA and Oracle DB [message #671206] Thu, 16 August 2018 13:40 Go to next message
vinicius
Messages: 2
Registered: August 2018
Junior Member
I have a Oracle RAC 11.2.0.3.0 2-node database running on SUSE Enterprise linux 11
And I'm confusing about the NUMA settings for this database:

SQL> !uname -a
Linux 2.6.32.12-0.7-default #1 SMP 2010-05-20 11:14:20 +0200 x86_64 x86_64 x86_64 GNU/Linux

Oracle DB Hidden parameters settings for NUMA:

SQL> SELECT a.ksppinm PNAME, c.ksppstvl PVAL, a.ksppdesc PDESC, b.ksppstdf PDFLT
  2  FROM x$ksppi a, x$ksppcv b, x$ksppsv c
  3  WHERE a.indx = b.indx
  4  AND a.indx = c.indx
  5  AND LOWER(a.ksppinm) LIKE '%numa%'
  6 ORDER BY 1;


PNAME                      PVAL                 PDESC
-------------------------- -------------------- ---------------------------------------------------
_NUMA_instance_mapping     Not specified        Set of nodes that this instance should run on
_NUMA_pool_size            Not specified        aggregate size in bytes of NUMA pool
_db_block_numa             1                    Number of NUMA nodes
_enable_NUMA_interleave    TRUE                 Enable NUMA interleave mode
_enable_NUMA_optimization  FALSE                Enable NUMA specific optimizations
_enable_NUMA_support       FALSE                Enable NUMA support and optimizations
_numa_buffer_cache_stats   0                    Configure NUMA buffer cache stats
_numa_trace_level          0                    numa trace event
_px_numa_stealing_enabled  TRUE                 enable/disable PQ granule stealing across NUMA nodes
_px_numa_support_enabled   TRUE                 enable/disable PQ NUMA support
_rm_numa_sched_enable      FALSE                Is Resource Manager (RM) related NUMA scheduled policy enabled
_rm_numa_simulation_cpus   0                    number of cpus for each pg for numa simulation in resource manager
_rm_numa_simulation_pgs    0                    number of PGs for numa simulation in resource manager


S.O. NUMA settings:

SQL> !numactl --show
policy: default
preferred node: current
physcpubind: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
cpubind: 0 1
nodebind: 0 1
membind: 0 1

SQL> !numactl --hardware
available: 2 nodes (0-1)
node 0 cpus: 1 3 5 7 9 11 13 15 17 19 21 23
node 0 size: 49141 MB
node 0 free: 10268 MB
node 1 cpus: 0 2 4 6 8 10 12 14 16 18 20 22
node 1 size: 49151 MB
node 1 free: 9902 MB
node distances:
node   0   1
  0:  10  20
  1:  20  10

cpu settings:
SQL> show parameter cpu

NAME                                 TYPE                             VALUE
------------------------------------ -------------------------------- ------------------------------
cpu_count                            integer                          24
parallel_threads_per_cpu             integer                          2
resource_manager_cpu_allocation      integer                          24

SQL> !lscpu
Architecture:          x86_64
CPU(s):                24
Thread(s) per core:    2
Core(s) per socket:    6
CPU socket(s):         2
NUMA node(s):          2
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 44
Stepping:              2
CPU MHz:               1600.000
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              12288K


What is the impact if I disable PQ NUMA support (_px_numa_support_enabled=FALSE), what is the expected behavior? It would disable NUMA for parallel queries or is there no changes since _enable_NUMA_support is already disabled (i.e. _enable_NUMA_support=FALSE)?
Is there any advantages on enable NUMA support for low latancy database?
Is there any place that explains how does NUMA works on Oracle DB?

Thanks in advance!
Vinicius


Re: NUMA and Oracle DB [message #671213 is a reply to message #671206] Fri, 17 August 2018 03:07 Go to previous messageGo to next message
gazzag
Messages: 1082
Registered: November 2010
Location: Bristol, UK
Senior Member
Has Oracle support told you to use the _enable_NUMA_support parameter? Generally speaking, underscore "hidden" parameters are not supported unless Oracle specifically tells you to use them.
Re: NUMA and Oracle DB [message #671227 is a reply to message #671213] Fri, 17 August 2018 08:21 Go to previous message
vinicius
Messages: 2
Registered: August 2018
Junior Member
No, but these parameters were not set on init.ora or spfile. I think it was taken by SO settings, since SO and HW are NUMA aware.
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