T-SQL to find the size of total and free physical memory

With VASummary(Size,Reserved,Free) AS
(SELECT
Size = VaDump.Size,
Reserved = SUM(CASE(CONVERT(INT, VaDump.Base)^0)
WHEN 0 THEN 0 ELSE 1 END),
Free = SUM(CASE(CONVERT(INT, VaDump.Base)^0)
WHEN 0 THEN 1 ELSE 0 END)
FROM
(
SELECT CONVERT(VARBINARY, SUM(region_size_in_bytes))
AS Size,
region_allocation_base_address AS Base
FROM sys.dm_os_virtual_address_dump
WHERE region_allocation_base_address <> 0x0
GROUP BY region_allocation_base_address
UNION
SELECT CONVERT(VARBINARY, region_size_in_bytes),
region_allocation_base_address
FROM sys.dm_os_virtual_address_dump
WHERE region_allocation_base_address = 0x0
)
AS VaDump
GROUP BY Size)

SELECT SUM(Size*Free)/1024 AS [Total avail mem, KB] ,CAST(MAX(Size) AS INT)/1024
AS [Max free size, KB]
FROM VASummary
WHERE Free <> 0


Best Practices Analyzer, Multi-Core Processors, and More by Nancy Michell