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Added new function vm_low_memory_state() that returns the current low 

memory status.
Added new B_NO_LOW_MEMORY constant for the usual case.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@15551 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler 2005-12-15 21:30:28 +00:00
parent 127e973b5d
commit 1534aa236c
2 changed files with 32 additions and 10 deletions
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2
headers/private/kernel/vm_low_memory.h
View File

@ -11,6 +11,7 @@
/* warning levels for low memory handlers */
enum {
B_NO_LOW_MEMORY = 0,
B_LOW_MEMORY_NOTE,
B_LOW_MEMORY_WARNING,
B_LOW_MEMORY_CRITICAL,
@ -23,6 +24,7 @@ extern "C" {
#endif
status_t vm_low_memory_init(void);
int32 vm_low_memory_state(void);
void vm_low_memory(size_t requirements);
// these calls might get public some day

40
src/system/kernel/vm/vm_low_memory.cpp
View File

@ -16,10 +16,13 @@
static const bigtime_t kLowMemoryInterval = 2000000; // 2 secs
// page limits
static const size_t kNoteLimit = 1024;
static const size_t kWarnLimit = 256;
static const size_t kCriticalLimit = 32;
static int32 sLowMemoryState = B_NO_LOW_MEMORY;
struct low_memory_handler : public DoublyLinkedListLinkImpl<low_memory_handler> {
low_memory_func function;
@ -48,24 +51,34 @@ call_handlers(int32 level)
}
static int32
compute_state(void)
{
uint32 freePages = vm_page_num_free_pages();
if (freePages >= kNoteLimit)
return B_NO_LOW_MEMORY;
// specify low memory level
if (freePages < kCriticalLimit)
return B_LOW_MEMORY_CRITICAL;
else if (freePages < kWarnLimit)
return B_LOW_MEMORY_WARNING;
return B_LOW_MEMORY_NOTE;
}
static int32
low_memory(void *)
{
while (true) {
snooze(kLowMemoryInterval);
uint32 freePages = vm_page_num_free_pages();
if (freePages >= kNoteLimit)
sLowMemoryState = compute_state();
if (sLowMemoryState < B_LOW_MEMORY_NOTE)
continue;
// specify low memory level
int32 level = B_LOW_MEMORY_NOTE;
if (freePages < kCriticalLimit)
level = B_LOW_MEMORY_CRITICAL;
else if (freePages < kWarnLimit)
level = B_LOW_MEMORY_WARNING;
call_handlers(level);
call_handlers(sLowMemoryState);
}
return 0;
}
@ -80,6 +93,13 @@ vm_low_memory(size_t requirements)
}
int32
vm_low_memory_state(void)
{
return sLowMemoryState;
}
status_t
vm_low_memory_init(void)
{