Thread: BUG #17307: Performance deviation between the multiple iterations (NOPM & TPM values).
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
Re: BUG #17307: Performance deviation between the multiple iterations (NOPM & TPM values).
PG Bug reporting form <noreply@postgresql.org> writes:
> 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%
According to who? Even if you'd provided an easily reproducible
example, I doubt we'd accept this as a bug. Adding more sessions
does not have zero cost.
regards, tom lane
Re: BUG #17307: Performance deviation between the multiple iterations (NOPM & TPM values).
We noticed the TPC-C performance(NOPM/TPM) deviation is >2% to 21% with virtual users(1 to 250 for 2 socket system) on running multiple iterations(5-6 runs).
Checked on different configurations/ system settings as below :
1.Reduced Max connection i.e., lower connections(example max_connections 1700 to 200 in postgres.conf )
2.Reduced warehouses in schema build i.e. pg_count_ware 800 to pg_count_ware 400/200
3.For each run/iteration rebuild schema(delete schema after results captured in each iteration and delete/drop tpcc, restart postgres and rebuild schema for next iteration)
4.For each Iteration unmount and mount /data forlder from SSD.
5.Numa settings like taskset/core pinning and SMT-OFF/SMT-ON.
6 Test run on different NUMA nodes like numactl --interleave=all or numa auto balancing.
7.With default PostgreSQL.conf and less virtual users(like 1,2,4,8,12,16,20) and small warehouse like 20 and pg_num_vu 4
8.Run HammerDB in client Machine and PostgreSQL in Master Machine.
Here are the questions:
1. What is the right way to test PostgreSQL with HammerDB for multiple iterations?
2. Is the performance deviation on multiple runs is expected because of raw Postgres performance?
3. Can "CPU usage, I/O volume, I/O Latency & HDD/SSD latency" be the reason for deviation?
Thanks
PG Bug reporting form <noreply@postgresql.org> writes:
> 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%
According to who? Even if you'd provided an easily reproducible
example, I doubt we'd accept this as a bug. Adding more sessions
does not have zero cost.
regards, tom lane