.net memory usage reporting difference between task manager and windbg/sos

Question

I have a .net application. In task manager it showing 249 MB usage in Memory (private working set) column. Then I attach windb and ran !address –summary command. Below is its result. The memory usage its showing in .NET heap(RegionUsageIsVAD) is 568 MB. Should these two values be same? Can anyone explain why is so much difference between the two values?

-------------------- Usage SUMMARY --------------------------
TotSize ( KB) Pct(Tots) Pct(Busy) Usage
22b7c000 ( 568816) : 27.12% 64.42% : RegionUsageIsVAD
4a1b3000 ( 1214156) : 57.90% 00.00% : RegionUsageFree
e8e6000 ( 238488) : 11.37% 27.01% : RegionUsageImage
1c00000 ( 28672) : 01.37% 03.25% : RegionUsageStack
0 ( 0) : 00.00% 00.00% : RegionUsageTeb
2dda000 ( 46952) : 02.24% 05.32% : RegionUsageHeap
0 ( 0) : 00.00% 00.00% : RegionUsagePageHeap
1000 ( 4) : 00.00% 00.00% : RegionUsagePeb
0 ( 0) : 00.00% 00.00% : RegionUsageProcessParametrs
0 ( 0) : 00.00% 00.00% : RegionUsageEnvironmentBlock
Tot: 7fff0000 (2097088 KB) Busy: 35e3d000 (882932 KB)

-------------------- Type SUMMARY --------------------------
TotSize ( KB) Pct(Tots) Usage
4a1b3000 ( 1214156) : 57.90% :
11ce9000 ( 291748) : 13.91% : MEM_IMAGE
9fe9000 ( 163748) : 07.81% : MEM_MAPPED
1a16b000 ( 427436) : 20.38% : MEM_PRIVATE

-------------------- State SUMMARY --------------------------
TotSize ( KB) Pct(Tots) Usage
2e2a0000 ( 756352) : 36.07% : MEM_COMMIT
4a1b3000 ( 1214156) : 57.90% : MEM_FREE
7b9d000 ( 126580) : 06.04% : MEM_RESERVE

Largest free region: Base 32ce9000 - Size 15377000 (347612 KB)

Answer 1

!address is just showing you address space usage. Some of the memory is paged out. The working set (memory actually paged in and in use) is much smaller.