[SQL] [效能] Hyper-Threading 與 SQL License限制core數

2016-07-13

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[SQL] [效能]
2016-08-30

Hyper-Threading對SQL的影響

https://support.microsoft.com/en-us/kb/322385

重點：若實體Processors已經用到飽和，超執行緒環境下的SQL Service會降低Performance
另外發現同版本、同名SQL ISO會被License限制最多可使用Processors數!! 問題是檔名是一樣的!!
所以問題是出在SQL License限制了Processors數，loading大時又因為開超執行續，performance變得更差

Performance

The performance of hyper-threaded environments varies. Conservative testing has shown 10 to 20 percent gains for SQL Server workloads, but the application patterns have a significant affect. You might find that some applications do not receive an increase in performance by taking advantage of hyper-threading. If the physical processors are already saturated, using logical processors can actually reduce the workload achieved.

For example, applications that cause high levels of contention can cause decreased performance in a hyper-threaded environment. We recommend that you test your application thoroughly to make sure that a hyper-threaded environment provides you the performance gain that you want versus the purchase of equivalent physical CPUs. Hyper-threading can be very helpful but hyper-threading cannot replace the full power of an additional physical CPU.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.