What can explain a large usage of shareable memory on Windows?

Question

I notice that 6.5 GB of my RAM is used as "shareable" memory. What can explain such a large usage?

I tried to list processes by size if shareable memory in the Resource Monitor, but I don't see anything outstanding.

I use Windows 7 SP1 x64 Ultimate.

After rebooting, the shareable memory is much smaller (~ 100 MB):

Solution

Shared memory just means that Windows isn't restricting other programs from using those memory cells for other applications. There's security checks for where programs can utilise memory cells and shareable means that you can use those alongside other applications that are currently using them also.

Most of the time this is because of DLL files or other files that have been loaded into memory, so loading another program with the same file or DLL will essentially just be sharing the same memory.

Comments

[David Schwartz]

What antivirus, if any, do you use? AVG?

[Franck Dernoncourt]

@DavidSchwartz Avast is installed but disabled.

[Jamie Hanrahan]

What is much more troubling is that of that 6.5 GB practically all of it is on your modified page list. This tells me that your system does not have a pagefile - and needs one badly.

[Franck Dernoncourt]

@JamieHanrahan Thanks. Why not having a pagefile would increase the size of the shared memory?

[Jamie Hanrahan]

A pagefile would allow the memory manager to write all of those modified shared pages (apparently part of a "pagefile-backed section") out to disk. Then they would be released to the Standby page list, where they would be part of "Available" RAM and could be used by other processes. Or for other use by the same process, for that matter. As it is, without a PF, they're just stuck on the Modified page list. You would still have the same amount of shared memory in terms of the virtual address space allocation, but not physical (RAM).

[MaxV]

Same problem for me, 19Gb of sharable!!!

[Frédéric Loyer]

EXE files are also shared since we can launch 2 processes which point to the same program file.