How can I invalidate the file system cache?
I've written a simple command-line utility to do that: FlushFileCache
It relies on the undocumented NtSetSystemInformation functions, and can flush the various other memory pools as well.
At least on Windows 7, it seems that attempting to open a volume handle without FILE_SHARE_WRITE sharing permissions causes the file system cache to be invalidated, even if the creation fails.
Thus I made a program that simply calls CreateFile to this end.
Download the program* from its Base64 version here:
<!-- Click "Run Snippet", then Right-Click -> Save As... -->
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// Usage: ClearCache C: D:
#include <tchar.h>
#include <stdio.h>
#include <windows.h>
int _tmain(int argc, LPTSTR argv[]) {
LPCTSTR DOS_PREFIX = _T("\\\\.\\");
for (int i = 1; i < argc; i++) {
LPTSTR arg = argv[i];
LPTSTR path = (LPTSTR)calloc(
_tcslen(arg) + _tcslen(DOS_PREFIX) + 1, sizeof(*arg));
__try {
if (_istalpha(arg[0]) && arg[1] == _T(':') &&
(arg[2] == _T('\0') ||
arg[2] == _T('\\') && arg[3] == _T('\0')))
{ _tcscat(path, DOS_PREFIX); }
_tcscat(path, arg);
HANDLE hFile = CreateFile(path,
FILE_READ_DATA, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0, NULL);
if (hFile != INVALID_HANDLE_VALUE) { CloseHandle(hFile); }
else {
DWORD le = GetLastError();
if (le != ERROR_SHARING_VIOLATION && le != ERROR_ACCESS_DENIED)
{
_ftprintf(stderr, _T("Error %d clearing %s\n"), le, argv[i]);
return le;
}
}
} __finally { free(path); }
}
return 0;
}
*Just for fun, see if you can figure out what the executable does by disassembling it. It's not your typical executable. :)