The problem
After making several performance fixes, notable among them being
the kernel mutex split and the new handling of read-only
transaction and in particular non-locking auto-commit read-only
transactions, we weren’t seeing any increase in transaction per
second (TPS) on our high-end hardware. On this one particular
host, a 24 core with 2 threads per core host. The TPS using
Sysbench was a tepid 5.6K at 16 threads and more or less
plateaued till 1K user threads. No matter what config setting we
used, we would more or less end up with the same result.
We ended up getting together for a meeting at Paris to discuss this issue and during the brain storming, one of the potential issues that cropped up was the effect of cache coherence and/or false sharing. After using …
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