static int
vm_page_zero_check(void)
{
if (!idlezero_enable)
return (0);
/*
* Attempt to maintain approximately 1/2 of our free pages in a
* PG_ZERO'd state. Add some hysteresis to (attempt to) avoid
* generally zeroing a page when the system is near steady-state.
* Otherwise we might get 'flutter' during disk I/O / IPC or
* fast sleeps. We also do not want to be continuously zeroing
* pages because doing so may flush our L1 and L2 caches too much.
*/
if (zero_state && vm_page_zero_count >= ZIDLE_LO(cnt.v_free_count))
return (0);
if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count))
return (0);
return (1);
}
/*
* Attempt to maintain approximately 1/2 of our free pages in a
* PG_ZERO'd state. Add some hysteresis to (attempt to) avoid
* generally zeroing a page when the system is near steady-state.
* Otherwise we might get 'flutter' during disk I/O / IPC or
* fast sleeps. We also do not want to be continuously zeroing
* pages because doing so may flush our L1 and L2 caches too much.
*
* Returns non-zero if pages should be zerod.
*/
static int
vm_page_zero_check(void)
{
if (idlezero_enable == 0)
return (0);
if (zero_state == 0) {
/*
* Wait for the count to fall to LO before starting
* to zero pages.
*/
if (vm_page_zero_count <= ZIDLE_LO(vmstats.v_free_count))
zero_state = 1;
} else {
/*
* Once we are zeroing pages wait for the count to
* increase to HI before we stop zeroing pages.
*/
if (vm_page_zero_count >= ZIDLE_HI(vmstats.v_free_count))
zero_state = 0;
}
return (zero_state);
}
