Sysbench tests on PG12

Was running a few sysbench tests in Postgres12.

Sysbench Test Config

oltp-readwrite-custom

Threads - 500

Machine: 16 core 64G

In PG server:

shared_buffers: 16GB

maintenance_work_memory: 16GB

checkpoint_timeout: 1h

max_wal_size: 10GB

wal_sync_method: 'open_sync'

effective_cache_size: 32GB

wal_buffers: -1

wal_compression: on

Got some qps dips.

Changed fsync and full_page_rewrite to 'off'.

Which helped in avoiding these many long dips in performance:

But fsync ensures DBMS consistency. So, instead of that can I change a few other configurations to avoid these inconsistent performance dips ?

Regards,

Subhrajyoti