Re: [PERFORM] Dbt2 with postgres issues on CentOS-5.3‏

From: Mark Wong <markwkm(at)gmail(dot)com>
To: MUHAMMAD ASIF <anaeem(dot)it(at)hotmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: [PERFORM] Dbt2 with postgres issues on CentOS-5.3‏
Date: 2010-04-22 01:10:35
Message-ID: n2y70c01d1d1004211810m64b14ab0t700a0b2f5b3cc0a1@mail.gmail.com
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2010/4/20 MUHAMMAD ASIF <anaeem(dot)it(at)hotmail(dot)com>:
> Hi,
>
> I am using dbt2 on Linux 64 (CentOS release 5.3 (Final)) . I have compiled
> latest postgresql-8.4.3 code on the machine and run dbt2 against it. I am
> little confused about the results. I ran dbt2 with the following
> configuration i.e.
>
> DBT2 Options :
>     WAREHOUSES=75
>     DB_CONNECTIONS=20
>     REGRESS_DURATION=1 #HOURS
>     REGRESS_DURATION_SEC=$((60*60*$REGRESS_DURATION))
>
> DBT2 Command :
>         ./dbt2-pgsql-create-db
>         ./dbt2-pgsql-build-db -d $DBDATA -g -r -w $WAREHOUSES
>         ./dbt2-run-workload -a pgsql -c $DB_CONNECTIONS -d
> $REGRESS_DURATION_SEC -w $WAREHOUSES -o $OUTPUT_DIR
>         ./dbt2-pgsql-stop-db
>
> I am not able to understand the sar related graphs. Iostat,mpstat and vmstat
> results are similar but
> sar results are strange. I tried to explore the dbt2 source code to find
> out the how graphs are drawn and why sar results differ.DBT2.pm : 189 reads
> sar.out and parse it and consider 1 minute elapsed time between each record
> i.e.

That is certainly a weakness in the logic of the perl modules in
plotting the charts accurately. I wouldn't be surprised if the other
stat tools suffer the same problem.

Regards,
Mark

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