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Is there any way to force the WorkingSet of a process to be 1GB in C++?
We would like to increase the WorkingSet of a .NET process to 1GB, in advance, to avoid page faults.
Is there a way to do this in .NET?
Update
Unfortunately, it appears that even if we do a call to SetProcessWorkingSetSizeEx, the garbage collection trims the working set down anyway, bypassing MinWorkingSet (see “Automatic GC.Collect() in the diagram below).
In the picture below, is there a way to lock the process WorkingSet (the green line) to 1GB, to avoid the spike in page faults (the red lines) that occur when allocating new memory into the process?
The reason this would be awesome is that every time a page fault occurs, it blocks the thread for 250us, which hits application performance badly.
Update
Quote from: “Windows via C/C++, Fifth Edition, Jeffrey Richter (Wintellect)”
Calls to SetProcessWorkingSetSize by an individual process are ignored
unless the process is just trying to empty its working set. To set
this limit, specify the JOB_OBJECT_LIMIT_WORKINGSET flag in the
LimitFlags member.
This book is implying that the only way to set the WorkingSet is by assigning the process to a Job Object and setting JOB_OBJECT_LIMIT_WORKINGSET and MinimumWorkingSetSize.
Update
SetProcessWorkingSetSizeEx has absolutely nothing to do with soft page faults. It only refers to hard page faults, as it prevents memory in the current WorkingSet being paged out to the hard drive.
Update
It turns out that the only method to increase the WorkingSet is to run .NET using an extremely specialized CLR Host written in C++ (see my answer below).
The only way that we could find to increase the WorkingSet of a process under .NET, to reduce soft page faults, was to run the entire .NET application under a custom CLR Host. This is a non-trivial exercise, requiring about 800 lines of custom written, rather dense C++ code. The C++ code intercepts the .NET calls to the Win32 memory management methods, altering the behavior of the .NET runtime so it doesn’t free memory as aggressively as it normally would.
This has the effect of incurring all of the soft page faults when the application starts up, so that during normal application execution, the number of soft page faults in the .NET app drops pretty much to zero.
This means that the application may be memory hungry, but it runs faster. In other words, we are sacrificing memory usage for increased realtime performance.