Oninit BenchIt Toolkit: AUTO_READAHEAD

Informix 11.7xC4 introduced a new feature, automatic readahead

Control Test

The initial timings shown below where with RA_PAGES/THRESHOLD of 32:8 and AUTO_READAHEAD of zero. RA_THRESHOLD is now deprecated so the effective values would be 32:16

 
        Load    Trans   Run   TPS        Avg Tran
                        Time               Time
1       5       372377  300 1241.257     0.000806
1       10      673624  300 2245.413     0.000445
1       20      1167870 300 3892.900     0.000257
1       30      1600505 300 5335.017     0.000187
1       40      1818320 300 6061.067     0.000165
1       50      1894979 300 6316.597     0.000158
1       60      1838675 301 6108.555     0.000164

Test One

Setting RA_PAGES to 128 as per the documented recommendations got the following results

 
1       5       359456  300 1198.187     0.000835
1       10      654120  300 2180.400     0.000459
1       20      1197687 300 3992.290     0.000250
1       30      1569119 300 5230.396     0.000191
1       40      1855230 300 6184.100     0.000162
1       50      1880197 300 6267.323     0.000160
1       60      1904072 300 6346.907     0.000158

Test Two

Setting AUTO_READAHEAD to 1 and removing RA_PAGES and RA_THRESHOLD from ONCONFIG

 
1       5       353282  300 1177.607     0.000849
1       10      649529  300 2165.097     0.000462
1       20      1186065 300 3953.550     0.000253
1       30      1613849 300 5379.497     0.000186
1       40      1840255 300 6134.183     0.000163
1       50      1887244 300 6290.813     0.000159
1       60      1904652 300 6348.840     0.000158

Test Three

Setting AUTO_READAHEAD to 2 and removing RA_PAGES and RA_THRESHOLD from ONCONFIG

 
1       5       368905  300 1229.683     0.000813
1       10      669017  300 2230.057     0.000448
1       20      1166842 300 3889.473     0.000257
1       30      1596006 300 5320.020     0.000188
1       40      1850934 301 6149.282     0.000163
1       50      1889501 300 6298.336     0.000159
1       60      1877632 300 6258.773     0.000160

Test Four

With AUTO_READAHEAD disabled by setting RA_PAGES to zero

 
1       5       367315  300 1224.383     0.000817
1       10      670680  300 2235.600     0.000447
1       20      1215492 300 4051.640     0.000247
1       30      1634854 300 5449.513     0.000184
1       40      1881980 300 6273.267     0.000159
1       50      1914204 300 6380.680     0.000157
1       60      1896624 300 6322.080     0.000158