I’ve been working with the folks working on OpenSolaris for a few months now providing advice and input on getting MySQL and the connectors (C/ODBC and C/J) installed as a standard component. Having got the basics in, the team are now looking at adding both 32-bit and 64-bit packages.

The question raised at the end of last week was whether OpenSolaris should enable 64-bit builds by default in 64-bit installations, and whether there was a noticeable performance difference that would make this worthwhile.

I did some initial tests on Friday which showed that there was a small increase (10-15%) of the packaged 64-bit installations over 32-bit under x86 using snv_81. Tests were executed using the included sql-bench tool, and this was a single execution run of each package for 5.0.56. Transactions are missing because I hadn’t enabled transactions in the tests.

There are some significant differences there (like the 55% increase on SELECT speeds, for example), but a single execution is never a good test. Also, it’s unclear whether the differences are between the compilations, the platform or just pure coincidence. This requires further investigation.

As a coincidence, Krish Shankar posted these notes on using SunStudio 11 and SunStudio 12 and the right compiler flags to get the best optimization.

I decided to do 10-pass iterations of sql-bench and compare both 32-bit and 64-bit standard builds, the 32-bit standard builds against Krish’s optimizations, and finally 32-bit and 64-bit optimized builds.

Some notes on all the tests:

• All builds are 5.0.56
• All tests are run on SunOS 5.11, snv_81
• Tests are executed on the same OS and machine running in 64-bit. The SPARC tests are on an UltraSPARC IIIi@1.28GHz Workstation with 1GB RAM; x86 are on a Dell T105, Opteron 1212 with 4GB RAM. Of course we’re not comparing machine speed, just 32-bit binaries over 64-bit.
• All results are in seconds; lower values mean faster performance.
• In all tests I’m using the built-in defaults (i.e. no my.cnf anywhere) so as to simulate a standardized installation.

Let’s first look at x86 and the 32-bit standard and 32-bit optimized builds:

The standard build uses gcc instead of SunStudio, but I don’t get the same performance increases that Krish saw – in fact, I see reductions in performance, not improvements at all. I’m going to rebuild and retest, because I’m convinced there’s a problem here with the builds that I’m not otherwise seeing. I certainly don’t expect to get results that show a 27% reduction in insert speed. That said, a 10% big-table increase is interesting. I’ll redo these builds and find out if the slow down is as marked as it here.

Here’s the comparison for standard builds between 32-bit and 64-bit standard builds on x86:

There are some incredible differences here – more than 50% increase in SELECT, and 30% for the big-tables test show that there is some advantage to having the 64-bit builds on x86 enabled.

Unfortunately I’ve had problems with the 64-bit optimized builds on my machine, so I haven’t completed optimized test comparisons.

On SPARC, Sun Studio is used as the default compiler, and the standard 32-bit and 64-bit show little difference:

Overall, a pretty insignificant difference here.

Now let’s compare the standard and optimized builds using Krish’s flags on SPARC:

The tests here show little significant difference between the standard and the optimized builds, although 6-7% would probably be enough to prefer an optimized build if you wanted to build your own.

Now let’s compare the optimized, Sun Studio 12 builds running in 32-bit and 64-bit:

The differences are virtually non-existent, and taking the reductions and increases in performance overall, there’s probably little difference.

The overall impression is that on x86 the improvement of 64-bit over 32-bit is significant enough that it’s probably a good idea to make 64-bit the default. On SPARC, the difference in the optimized builds is so slight that for compatibility reasons alone, 32-bit would probably make a better default.

I’ll probably be re-running these tests over the next week or so (particularly the x86 so I can get a true comparison of the 64-bit optimized improvements), and I’ll try the T1000 which I upgraded to snv_81 over the weekend, but I think indications are good enough to make a reasonable recommendation of 64-bit over 32-bit.