Re: [PERFORM] Speed differences between two servers - Mailing list pgsql-performance

From Vincent Veyron
Subject Re: [PERFORM] Speed differences between two servers
Date
Msg-id 20170509002441.994488df4bd1a216ec15f8e3@wanadoo.fr
Whole thread Raw
In response to Re: [PERFORM] Speed differences between two servers  (Scott Marlowe <scott.marlowe@gmail.com>)
Responses Re: [PERFORM] Speed differences between two servers  (Scott Marlowe <scott.marlowe@gmail.com>)
List pgsql-performance
On Mon, 8 May 2017 12:48:29 -0600
Scott Marlowe <scott.marlowe@gmail.com> wrote:

Hi Scott,

Thank you for your input.

>
> The most likely cause of the difference would be that one server IS
> honoring fsync requests from the db and the other one isn't.
>
> If you run pgbench on both (something simple like pgbench -c 1 -T 60,
> aka one thread for 60 seconds) on a machine running on a 7200RPM hard
> drive, you should get approximately 120 transactions per second

Here are the results :

#Kimsufi
pgbench -c 1 -T 60 test
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
query mode: simple
number of clients: 1
number of threads: 1
duration: 60 s
number of transactions actually processed: 6618
latency average: 9.069 ms
tps = 110.270771 (including connections establishing)
tps = 110.283733 (excluding connections establishing)

#Online
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
query mode: simple
number of clients: 1
number of threads: 1
duration: 60 s
number of transactions actually processed: 1150
latency average: 52.317 ms
tps = 19.114403 (including connections establishing)
tps = 19.115739 (excluding connections establishing)


>
> > -Why are regular queries much faster on this same server?
>
> That's a whole nother subject. Most likely the faster machine can fit
> the whole db in memory, or has much faster memory, or the whole
> dataset is cached etc etc.
>

The dataset is small (35 MB) and both servers have 4GB memory. It appears to be faster on the Online server.

using 'dmidecode -t 17' :

#Kimsufi
Memory Device
    Array Handle: 0x0016
    Error Information Handle: Not Provided
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 2048 MB
    Form Factor: DIMM
    Set: None
    Locator: SO DIMM 0
    Bank Locator: Channel A DIMM0
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1066 MHz
    Manufacturer: 0x0000000000000000
    Serial Number: 0x00000000
    Asset Tag: Unknown
    Part Number: 0x000000000000000000000000000000000000
    Rank: Unknown
    Configured Clock Speed: 1066 MHz

[repeated for second locator]

#Online
Memory Device
    Array Handle: 0x0015
    Error Information Handle: No Error
    Total Width: Unknown
    Data Width: Unknown
    Size: 4096 MB
    Form Factor: DIMM
    Set: None
    Locator: DIMM0
    Bank Locator: BANK 0
    Type: DDR3
    Type Detail: Synchronous Unbuffered (Unregistered)
    Speed: 1600 MHz
    Manufacturer: <BAD INDEX>
    Serial Number: <BAD INDEX>
    Asset Tag: <BAD INDEX>
    Part Number: <BAD INDEX>
    Rank: 1
    Configured Clock Speed: 1333 MHz
    Minimum voltage:  Unknown
    Maximum voltage:  Unknown
    Configured voltage:  Unknown




--
                    Bien à vous, Vincent Veyron

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