In addition to absolute performance rates, it is interesting to examine the scaling properties of the different processors, i.e. the gains that can be made by adding extra cores. Again, we only consider the heavy load situations, since that is where the extra computing power is most appropriate. There is only one way to measure the performance with one to four cores, but for two cores there are two possibilities: either two processors use one core, or one (dualcore) processor is used. In spite of the seemingly substantial influence this might have on memory access (Opteron) and the amount of cache per core (Woodcrest), the difference turns out to be small. Since a choice needs to be made, we have selected the best result of the two - like we did on the previous pages.
 |
 | Scaling behaviour Woodcrest | |
|
| MySQL 4.1.20 (from 1 to 2 cores) |      47% | |
|
| MySQL 4.1.20 (from 2 to 4 cores) | 15% | |
|
| MySQL 5.0.20a (from 1 to 2 cores) |    34% | |
|
| MySQL 5.0.20a (from 2 to 4 cores) | 14% | |
|
| PostgreSQL 8.2-dev (from 1 to 2 cores) |    84% | |
|
| PostgreSQL 8.2-dev (from 2 to 4 cores) | 82% | |
|
|
| Scaling behaviour Dempsey* | |
|
| MySQL 4.1.20 (from 1 to 2 cores) | 42% | |
|
| MySQL 4.1.20 (from 2 to 4 cores) | 19% | |
|
| MySQL 5.0.20a (from 1 to 2 cores) | 44% | |
|
| MySQL 5.0.20a (from 2 to 4 cores) | 21% | |
|
| PostgreSQL 8.2-dev (from 1 to 2 cores) | 95% | |
|
| PostgreSQL 8.2-dev (from 2 to 4 cores) | 88% | |
|
|
| Scaling behaviour Socket F | |
|
| MySQL 4.1.20 (from 1 to 2 cores) | 48% | |
|
| MySQL 4.1.20 (from 2 to 4 cores) | 25% | |
|
| MySQL 5.0.20a (from 1 to 2 cores) | 44% | |
|
| MySQL 5.0.20a (from 2 to 4 cores) | 21% | |
|
| PostgreSQL 8.2-dev (from 1 to 2 cores) | 85% | |
|
| PostgreSQL 8.2-dev (from 2 to 4 cores) | 80% | |
|
|
| Scaling behaviour Socket 940 | |
|
| MySQL 4.1.20 (from 1 to 2 cores) | 50% | |
|
| MySQL 4.1.20 (from 2 to 4 cores) | 28% | |
|
| MySQL 5.0.20a (from 1 to 2 cores) | 45% | |
|
| MySQL 5.0.20a (from 2 to 4 cores) | 23% | |
|
| PostgreSQL 8.2-dev (from 1 to 2 cores) | 90% | |
|
| PostgreSQL 8.2-dev (from 2 to 4 cores) | 81% | |
|
The differences are not huge, but nevertheless present. Especially in MySQL, Woodcrest appears weak compared to the Opterons. The performance improvement that is obtained by doubling the number of cores diminishes quickly in all CPUs, but where AMD manages to gain 21% to 28%, the Xeon cannot achieve more than 15% better performance. Of course Intel has the upper hand of a strong core, but for the future it could see problems with quadcores and systems with four or more sockets.
|
| Average per processor* | |
|
| Woodcrest (from 1 to 2 cores) | 55% | |
|
| Woodcrest (from 2 to 4 cores) | 37% | |
|
| Dempsey (from 1 to 2 cores) | 60% | |
|
| Dempsey (from 2 to 4 cores) | 43% | |
|
| Opteron (DDR) (from 1 to 2 cores) | 62% | |
|
| Opteron (DDR) (from 2 to 4 cores) | 44% | |
|
| Opteron (DDR2) (from 1 to 2 cores) | 62% | |
|
| Opteron (DDR2) (from 2 to 4 cores) | 43% | |
|
|
| Average per database* | |
|
| MySQL 4.1.20 (from 1 to 2 cores) | 48% | |
|
| MySQL 4.1.20 (from 2 to 4 cores) | 22% | |
|
| MySQL 5.0.20a (from 1 to 2 cores) | 43% | |
|
| MySQL 5.0.20a (from 2 to 4 cores) | 21% | |
|
| PostgreSQL 8.2-dev (from 1 to 2 cores) | 89% | |
|
| PostgreSQL 8.2-dev (from 2 to 4 cores) | 83% | |
|
*) In all Dempsey tests, HyperThreading was switched off in MySQL, but for PostgreSQL it was switched on
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