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pgbench results arent accurate - Mailing list pgsql-performance

From Mariel Cherkassky
Subject pgbench results arent accurate
Date
Msg-id CA+t6e1nofA5=w1HnknWUTvXsmBryqiPEzgdouiqgdYL0tL1Uuw@mail.gmail.com
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Responses RE: pgbench results arent accurate
Re: pgbench results arent accurate
Re: pgbench results arent accurate
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Hey,
I installed a new postgres 9.6 on both of my machines. I'm trying to measure the differences between the performances in each machine but it seems that the results arent accurate.
I did 2 tests : 

1)In the first test the scale was set to 100 :
pgbench -i -s 100 -U postgres -d bench -h machine_name
pgbench -U postgres -d bench  -h machine_name -j 2 -c 16 -T 300
RUN   TPS - machine1TPS-machine2
1697555
2732861
3784842


2)In this test the scale was set to 10000 : 
pgbench -i -s 10000 -U postgres -d bench -h machine_name
pgbench -U postgres -d bench --progress=30 -h machine_name -j 2 -c 16 -T 300 
RUNTPS-MACHINE1 TPS-MACHINE2
110360
26366
37483
45661
57553
67360
76253

In both cases after the initalization I restarted the database and cleared the cashe(echo 1 > /proc/sys/vm/drop_caches) one time. During all the runs I didnt shutdown the machine.

Now, I was hopping the the tps will be almost the same in each machine for all the runs. In other words, I wanted to see that the tps in machine1 during all the tps are almost the same but I see that the values arent accurate.

Any idea what might cause the differences in every run ?

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