Performance Tuning with SQL Server Dynamic Management Views

• cpu_count – number of logical processors on the computer.
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Chapter 7: OS and Hardware Interaction
• hyperthread_ratio – ratio of logical to physical processors (cores). For example,
on a dual-core processor with hyper-threading turned off, this value would be 2. If
hyper-threading were enabled, the value would be 4. Note that this ratio value does not
discern between hyper-threading and multi-core (e.g. a quad-core processor with no
hyper-threading would also return a value of 4).
• physical_memory_in_bytes – total amount of physical RAM installed on the
computer or, at least, the amount of RAM that the OS believes it has available (a
distinction that is particularly relevant when dealing with virtual environments).
• virtual_memory_in_bytes – amount of virtual RAM available to the process in
user mode. This can differ depending on the OS. On a 32-bit OS, variations can be
based on the 3-GB switch or, in Vista and later, the IncreaseUserVa switch (set using
the bcdedit utility).
• max_workers_count – maximum number of workers that can be created. Workers
do the work for SQL Server and are generally equivalent to threads, unless running in
"lightweight pooling" server configuration, in which case it corresponds to a fiber
(for a deeper understanding, go to http://msdn.microsoft.com/en-us/library/
ms189267.aspx).
• scheduler_total_count – total number of schedulers configured, including the
system schedulers, such as the one that handles Dedicated Administrator Connection
(DAC) connections (corresponds to the result of: select count(*) from sys.
dm_os_schedulers).
• scheduler_count – current number of schedulers that are visible to user processes
(corresponds to the result of select count(*) from sys.dm_os_schedulers
where status = 'VISIBLE ONLINE').
• os_priority_class – Windows scheduling priority for the SQL Server process.
Essentially, a high value will allow SQL Server to use a higher than normal allocation
of OS resources. Domain: 64 (low), 16384 (below normal), 32 (normal), 32768 (above
normal), 256 (real-time), 128 (high). The default is "normal," unless the priority boost