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Re: pgbench results arent accurate - Mailing list pgsql-performance

From Mariel Cherkassky
Subject Re: pgbench results arent accurate
Date
Msg-id CA+t6e1mzeBgT+F3jm0jjChaGSh+G20ZcmG+Bdfi83+NCbeCL7A@mail.gmail.com
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In response to pgbench results arent accurate  (Mariel Cherkassky <mariel.cherkassky@gmail.com>)
Responses Re: pgbench results arent accurate  (Mark Kirkwood <mark.kirkwood@catalyst.net.nz>)
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As Greg suggested, update you all that each vm has its own dedicated esx. Every esx has it`s own local disks.
I run it one time on two different servers that has the same hardware and same postgresql db (version and conf). The results : 
pgbench -i -s 6  pgbench -p 5432 -U postgres
 pgbench -c 16 -j 4 -T 5 -U postgres pgbench
MACHINE 1
starting vacuum...end.
transaction type: <builtin: TPC-B (sort of)>
scaling factor: 6
query mode: simple
number of clients: 16
number of threads: 4
duration: 5 s
number of transactions actually processed: 669
latency average = 122.633 ms
tps = 130.470828 (including connections establishing)
tps = 130.620286 (excluding connections establishing)

MACHINE 2

pgbench -c 16 -j 4 -T 600 -U postgres -p 5433 pgbench
starting vacuum...end.
transaction type: <builtin: TPC-B (sort of)>
scaling factor: 6
query mode: simple
number of clients: 16
number of threads: 4
duration: 600 s
number of transactions actually processed: 2393723
latency average = 4.011 ms
tps = 3989.437514 (including connections establishing)
tps = 3989.473036 (excluding connections establishing)

any idea what can cause such a difference ? Both of the machines have 20core and 65GB of ram.

‫בתאריך יום ה׳, 13 בדצמ׳ 2018 ב-15:54 מאת ‪Mariel Cherkassky‬‏ <‪mariel.cherkassky@gmail.com‬‏>:‬
Ok, I'll do that.  Thanks .

‫בתאריך יום ה׳, 13 בדצמ׳ 2018 ב-15:54 מאת ‪Greg Clough‬‏ <‪Greg.Clough@ihsmarkit.com‬‏>:‬

Hmmm... sounds like you’ve got most of it covered.  It may be a good idea to send that last message back to the list, as maybe others will have better ideas.

 

Greg.

 

From: Mariel Cherkassky <mariel.cherkassky@gmail.com>
Sent: Thursday, December 13, 2018 1:45 PM
To: Greg Clough <Greg.Clough@ihsmarkit.com>
Subject: Re: pgbench results arent accurate

 

Both of the machines are the only vms in a dedicated esx for each one. Each esx has local disks.

 

On Thu, Dec 13, 2018, 3:05 PM Greg Clough <Greg.Clough@ihsmarkit.com wrote:

> I installed a new postgres 9.6 on both of my machines.

 

Where is your storage?  Is it local, or on a SAN?  A SAN will definitely have a cache, so possibly there is another layer of cache that you’re not accounting for.

 

Greg Clough.

 


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