I have been benchmarking Waffle Grid using the new Innodb Plugin 1.03 the past couple of days. Let me say the plugin is fast. Which got me thinking, generally when you fix a bottleneck another area becomes a bottleneck… its a vicious cycle really. I figured why not benchmarks several different settings just to see what sort of improvement or detriment we get in Inno. This hopefully will lead to the next place to look for potential performance improvements. For the test I chose a somewhat IO bound setup and a CPU bound setup.
The IO bound setup was a 20W test, 768M buffer pool.
The CPU boud setup was a 20W test, 5GB buffer pool.
So the IO bound test actually showed a larger impact then I was expecting:
30-35% overhead is actually huge… so this maybe an area that could be looked at to boost performance for IO bound workloads.
On the CPU side of things, I noticed something completely strange, and I had to rerun the tests several times just to make sure I got this right and did not reverse my findings:
Yep those are correct. In all my runs, I was seeing up to a 7% increase in performance by having the double write enabled. Which seems to counter logic, more writes should be slower (The three tests above represent the high/low/and average of 7 test runs ). I guess I could understand a mixed set of tests, where 3 tests showed it as slower, and 4 showed it faster … that could be attributed to tiny changes in the randomness of the tests… but in this case every test with the double write was faster. I am at a loss for why, but it now has me curious… what could cause such strange behavior? Not 100% sure, but I will add it to the ever growing list of thing I want to look at and dig into in the future.