CAP_CPU_PERCENT

Robert Davis looks at the CAP_CPU_PERCENT option in Resource Governor:

The need for this setting came about because MAX_CPU_PERCENT is not applied unless the server is busy. This could lead to a situation where queries in a low priority resource pool starts running while the server is idle and are allowed to consume all the CPU they can. Then high priority queries spin up, and they can’t immediately get the CPU they need due to the low priority queries not being capped. CAP_CPU_PERCENT came along and was designed to set a hard limit that the queries in a pool could not go over even if the server is idle. For example, if you cap the CPU at 25%, the queries in the pool will not exceed 25% no matter how idle the server is.

Problem solved, right?

When the end of a section is a yes/no question, the answer is usually “no.”  Read on before this burns you.

Resource Governor

Mark Wilkinson walks through Resource Governor:

Now that we know which statistics we can gather, we need to actually start gathering them. While the DMVs for Resource Governor are great, they will only give you an aggregate of the usage information since the last time the statistics were reset, or the last time services were restarted.

In most cases it makes sense to store your data in a separate table so you can calculate differentials between two time periods. For our example we are only going to be interested in request counts and CPU usage. For this, we will create the following table

Read the whole thing.

Resource Governor For R

Tomaz Kastrun describes using Resource Governor with Microsoft R Services:

Setting external resource pool for execution of R commands using sp_execute_external_script has proven extremely useful, especially in cases where you have other workers present, when you don’t want to overdo on data analysis and get to much resources from others (especially when running data analysis in production environment) or when you know that your data analysis will require maximum CPU and memory for a specific period. In such cases using and definingexternal resource pool is not only useful but highly recommended.

Resource governor is a feature that enables you to manage SQL Server workload and system resource consumption their limits. Limits can be configures for any workload in terms of CPU, Memory and I/O consumption. Where you have many different workloads on the same SQL Server, resource Governor helps allocate requested resources.

If you’re concerned about R soaking up all of your server’s memory, Resource Governor is a great way of limiting that risk.

Categories

April 2017
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