note
BrowserUk
<blockquote><i></i></blockquote>
<p>This displays the page fault count before and after allocating an 40960 byte chunk of memory from a heap, then freeing it and allocating it again.
<code>
#! perl -slw
use strict;
use Inline C => Config => LIBS => '-lpsapi.lib';
use Inline C => 'DATA', NAME => 'heap', CLEAN_AFTER_BUILD => 0;
my $heap = heapCreate( 0, 0, 1024 * 1024 );
my $space = heapAlloc( $heap, 0, 4096 * 10 );
heapFree( $heap, 0, $space );
$space = heapAlloc( $heap, 0, 4096 * 10 );
print heapSize( $heap, 0, $space );
__DATA__
__C__
#include <windows.h>
#include <psapi.h>
U32 heapCreate( U32 flags, U32 initial, int max ) {
return (U32) HeapCreate( flags, initial, max );
}
U32 heapAlloc( U32 hHeap, U32 flags, U32 size ) {
U32 pMem;
PROCESS_MEMORY_COUNTERS pmc;
pmc.cb = sizeof( PROCESS_MEMORY_COUNTERS );
GetProcessMemoryInfo( GetCurrentProcess(),
&pmc, sizeof( PROCESS_MEMORY_COUNTERS )
);
printf( "pagefaults before alloc of %d bytes: %d\n",
size, pmc.PageFaultCount
);
pMem = (U32)HeapAlloc( (HANDLE)hHeap, flags, (SIZE_T)size );
GetProcessMemoryInfo( GetCurrentProcess(),
&pmc, sizeof( PROCESS_MEMORY_COUNTERS )
);
printf( "pagefaults after alloc of %d bytes: %d\n",
size, pmc.PageFaultCount
);
return pMem;
}
U32 heapSize( U32 hHeap, U32 flags, U32 mem ) {
return (U32)HeapSize( (HANDLE)hHeap, flags, (LPVOID)mem );
}
U32 heapFree( U32 hHeap, U32 flags, U32 mem ) {
return (U32)HeapFree( (HANDLE)hHeap, flags, (LPVOID)mem );
}
</code>
<p>The output<code>
c:\test>HeapMem.pl
pagefaults before alloc of 40960 bytes: 952
pagefaults after alloc of 40960 bytes: 964
pagefaults before alloc of 40960 bytes: 964
pagefaults after alloc of 40960 bytes: 964
40960
c:\test>HeapMem.pl
pagefaults before alloc of 40960 bytes: 953
pagefaults after alloc of 40960 bytes: 965
pagefaults before alloc of 40960 bytes: 965
pagefaults after alloc of 40960 bytes: 965
40960
c:\test>HeapMem.pl
pagefaults before alloc of 40960 bytes: 953
pagefaults after alloc of 40960 bytes: 965
pagefaults before alloc of 40960 bytes: 965
pagefaults after alloc of 40960 bytes: 965
40960
</code>
<p>Shows that the first time, allocating 10 pages of memory results in 12 page faults. The second time none.
<div class="pmsig"><div class="pmsig-171588">
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