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Re: Benchmarking: How to identify bottleneck (limiting factor) andachieve "linear scalability"? - Mailing list pgsql-performance

From Saurabh Nanda
Subject Re: Benchmarking: How to identify bottleneck (limiting factor) andachieve "linear scalability"?
Date
Msg-id CAPz=2oG4zwxMAc200HCSyKmiOJg6JGaWJKTyQ3rFT_9nfm2KCA@mail.gmail.com
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In response to Re: Benchmarking: How to identify bottleneck (limiting factor) andachieve "linear scalability"?  (Nicolas Charles <nicolas.charles@normation.com>)
Responses Re: Benchmarking: How to identify bottleneck (limiting factor) andachieve "linear scalability"?  (Saurabh Nanda <saurabhnanda@gmail.com>)
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smartctl is a good start

Here's the output of `smartctl --xall /dev/sda` -- https://gist.github.com/saurabhnanda/ec3c95c1eb3896b3efe55181e7c78dde

I've disabled RAID so /dev/sda is the only disk which is being currently used.

I'm still seeing very weird numbers. There seems to be absolutely no difference in performance if I increase shared_buffers from 8MB to 2GB. Is there some other setting which needs to be changed to take advantage of the increase in shared_buffers? Also, something even weirder is happening for client=1.


+--------+--------------+----------------+
| client | Defaults [1] | buffers=2G [2] |
+--------+--------------+----------------+
| 1      | 348-475 (??) | 529-583 (??)   |
+--------+--------------+----------------+
| 4      | 436-452      | 451-452        |
+--------+--------------+----------------+
| 8      | 862-869      | 859-861        |
+--------+--------------+----------------+
| 12     | 1210-1219    | 1220-1225      |
+--------+--------------+----------------+

[1] Default settings
     checkpoint_completion_target=0.5 
     default_statistics_target=100 
     effective_io_concurrency=1 
     max_parallel_workers=8 
     max_parallel_workers_per_gather=2 
     max_wal_size=1024 MB
     max_worker_processes=20 
     min_wal_size=80 MB
     random_page_cost=4 
     shared_buffers=1024 8kB
     wal_buffers=32 8kB
     work_mem=4096 kB

[2] Increased shared_buffers
     checkpoint_completion_target=0.5 
     default_statistics_target=100 
     effective_io_concurrency=1 
     max_parallel_workers=8 
     max_parallel_workers_per_gather=2 
     max_wal_size=1024 MB
     max_worker_processes=20 
     min_wal_size=80 MB
     random_page_cost=4 
     shared_buffers=262144 8kB
     wal_buffers=2048 8kB
     work_mem=4096 kB

-- Saurabh.

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