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External Memory Pressure With SQL On Linux

Anthony Nocentino explains how SQL Server on Linux reacts to memory pressure:

We can use tools like ps, top and htop to look our are virtual and physical memory allocations. We can also look in the /proc virtual file system for our process and look at the status file. In here we’ll find the point in time status of a process, and most importantly the types of memory allocations for a process. We’ll get granular data on the virtual memory allocations and also the resident set size of the process. Here are the interesting values in the status file we’re going to focus on today.

  • VmSize – total current virtual address space of the process

  • VmRSS – total amount of physical memory currently allocated to the process

  • VmSwap – total amount of virtual memory currently paged out to the swap file (disk)

The differences are going to be interesting for people to troubleshoot later, particularly if you look at SOS_SCHEDULER_YIELD and give a knee-jerk reaction that the problem is with CPU.