Dbt2 with postgres issues on CentOS-5.3‏

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.
    ActivePerl-5.10.1.1007-i686-linux-glibc-2.3.2-291969/inst/lib/Test/Parser/Sar.pm : 266
        elapsed_time is a counter, with every record it increment to 1 (++$elapsed_time)
 
 Sar.out shows the following results i.e.
 
    08:54:47 PM   cswch/s
    ..
    ..
    09:21:47 PM   1809.46
    09:22:47 PM   2251.26
    09:23:47 PM   2151.27
    09:24:47 PM   2217.33
    09:27:01 PM   2189.83
    09:29:02 PM   2155.13
    09:30:02 PM   2048.04
    09:32:19 PM   2033.16
    09:34:20 PM   2032.47
    09:36:20 PM   2006.02
    09:37:20 PM   1966.03
    09:39:35 PM   1974.77
    09:41:37 PM   1973.88
    09:42:37 PM   1960.65
    09:44:56 PM   1993.15
    09:45:56 PM   1989.46
    09:47:57 PM   2430.77
    09:48:57 PM   2416.64
    09:51:08 PM   2330.02
    09:53:19 PM   1738.46
    09:54:19 PM   2182.27
    09:55:19 PM   2221.31
    09:56:19 PM   2131.81
    09:57:19 PM   2183.47
    09:59:31 PM   2156.70
    10:01:32 PM   2114.38
    10:02:32 PM   2030.05
    10:04:51 PM   2059.56
    10:05:51 PM   1995.06
    10:08:09 PM   1355.43
    10:09:09 PM    218.73
    10:10:09 PM    175.13
    10:11:09 PM    168.30
    10:12:09 PM    168.58
    ..
    ..
It shows that sar results for each record is not after every 1 minute duration, it varies.  Is it expected or there are some bugs in CentOS default sar package (sysstat-7.0.2-3.el5). I tried latest package sysstat-9.0.6.1 from but it behaving the same. Systat utilities depends on procfs, is there something wrong with the system ?. Thanks.
 
Best Regards,
Asif Naeem