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POWhat is the exact difference between MEM_RESERVE and MEM_COMMIT states?
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  1. POWhat is the exact difference between MEM_RESERVE and MEM_COMMIT states?
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    copied!<p>As I understand it MEM_RESERVE is actually 'free' memory, ie available to be used by my process, but just hasn't been allocated yet? Or it was previously allocated, but had since been freed? </p> <p>Specifically, see in my !address output below how I am nearly out of virtual address space (99900 KB free, 2307872 as MEM_PRIVATE. But the states shows that 44.75% of that is actually MEM_RESERVE. Does that mean it is actually free, in my process...but maybe fragmented?</p> <pre><code>0:000&gt; !address -summary --------- PEB a8bd8000 not found ---- -------------------- Usage SUMMARY -------------------------- TotSize ( KB) Pct(Tots) Pct(Busy) Usage 259af000 ( 616124) : 22.29% 23.12% : RegionUsageIsVAD 618f000 ( 99900) : 03.61% 00.00% : RegionUsageFree 13e22000 ( 325768) : 11.78% 12.22% : RegionUsageImage 42c04000 ( 1093648) : 39.56% 41.04% : RegionUsageStack 42d000 ( 4276) : 00.15% 00.16% : RegionUsageTeb 2625d000 ( 625012) : 22.61% 23.45% : RegionUsageHeap 0 ( 0) : 00.00% 00.00% : RegionUsagePageHeap 0 ( 0) : 00.00% 00.00% : RegionUsagePeb 1000 ( 4) : 00.00% 00.00% : RegionUsageProcessParametrs 1000 ( 4) : 00.00% 00.00% : RegionUsageEnvironmentBlock Tot: a8bf0000 (2764736 KB) Busy: a2a61000 (2664836 KB) -------------------- Type SUMMARY -------------------------- TotSize ( KB) Pct(Tots) Usage 618f000 ( 99900) : 03.61% : &lt;free&gt; 13e22000 ( 325768) : 11.78% : MEM_IMAGE 1e77000 ( 31196) : 01.13% : MEM_MAPPED 8cdc8000 ( 2307872) : 83.48% : MEM_PRIVATE -------------------- State SUMMARY -------------------------- TotSize ( KB) Pct(Tots) Usage 57235000 ( 1427668) : 51.64% : MEM_COMMIT 618f000 ( 99900) : 03.61% : MEM_FREE 4b82c000 ( 1237168) : 44.75% : MEM_RESERVE Largest free region: Base 7e4a1000 - Size 000ff000 (1020 KB) </code></pre> <p>FOLLOW UP:</p> <p>So in terms of my example, this process is reporting 'out of memory', but actually it COULD make allocations, but someone MEM_RESERVED more than they needed at that point, preventing someone else from even being able to allocate? </p>
 

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