BUG #17307: Performance deviation between the multiple iterations (NOPM & TPM values).

The following bug has been logged on the website:

Bug reference:      17307
Logged by:          HPC Researcher
Email address:      researcherhpc@gmail.com
PostgreSQL version: 14.0
Operating system:   RHEL 8.4
Description:

NOPM values captured with HammerDB-v4.3 scripts (schema_tpcc.tcl and
test_tpcc.tcl ) for multiple trails.
The expected performance deviation between multiple trials should be less
than 2% 

Hardware configuration 
Architecture        x86_64 
CPU op-mode(s)      32-bit, 64-bit 
Byte Order:          Little Endian 
CPU(s):              256 
On-line CPU(s) list: 0-255 
Thread(s) per core:  2 
Core(s) per socket:  64 
Socket(s):           2 
NUMA node(s):        8 
L1d cache:           32K 
L1i cache:           32K  
L2 cache:            512K 
L3 cache:            16384K 
OS: RHEL8.4 
RAM SIZE:512 
SSD:1TB 



Postgresql.conf 

autovacuum_max_workers = 16 
autovacuum_vacuum_cost_limit = 3000 
checkpoint_completion_target = 0.9 
checkpoint_timeout = '15min' 
cpu_tuple_cost = 0.03 
effective_cache_size = '350GB' 
listen_addresses = '*' 
maintenance_work_mem = '2GB' 
max_connections = 1000 
max_wal_size = '128GB' 
random_page_cost = 1.1 
shared_buffers = '128GB' 
wal_buffers = '1GB' 
work_mem = '128MB' 
random_page_cost = 1.1 
effective_io_concurrency = 200  

HammerDB Scripts 
    >>cat schema.tcl 
    #!/bin/tclsh 
    dbset db pg 
    diset connection pg_host localhost 
    diset connection pg_port 5432 
    diset tpcc pg_count_ware 400 
    diset tpcc pg_num_vu 50 
    print dict 
    buildschema 
    waittocomplete 

RUN TEST on i.e. start with 1VU then 2, 4 etc 
      Virtual Users   Trail-1(NOPM) Trail-2(NOPM)    %diff     
        12        99390               92913                  6.516752  
        140        561429               525408                  6.415949  
        192        636016               499574                  21.4526  
        230        621644               701882                  12.9074