diff options
Diffstat (limited to 'sys/amd64/amd64/vm_machdep.c')
| -rw-r--r-- | sys/amd64/amd64/vm_machdep.c | 42 |
1 files changed, 23 insertions, 19 deletions
diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c index 297a10f..2e9e6aa 100644 --- a/sys/amd64/amd64/vm_machdep.c +++ b/sys/amd64/amd64/vm_machdep.c @@ -38,7 +38,7 @@ * * from: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91 * Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$ - * $Id: vm_machdep.c,v 1.115 1999/01/06 23:05:37 julian Exp $ + * $Id: vm_machdep.c,v 1.116 1999/01/29 08:36:42 dillon Exp $ */ #include "npx.h" @@ -590,31 +590,32 @@ int vm_page_zero_idle() { static int free_rover; + static int zero_state; vm_page_t m; int s; /* - * XXX - * We stop zeroing pages when there are sufficent prezeroed pages. - * This threshold isn't really needed, except we want to - * bypass unneeded calls to vm_page_list_find, and the - * associated cache flush and latency. The pre-zero will - * still be called when there are significantly more - * non-prezeroed pages than zeroed pages. The threshold - * of half the number of reserved pages is arbitrary, but - * approximately the right amount. Eventually, we should - * perhaps interrupt the zero operation when a process - * is found to be ready to run. + * 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 (cnt.v_free_count - vm_page_zero_count <= cnt.v_free_reserved / 2) - return (0); + + if (zero_state && vm_page_zero_count >= cnt.v_free_count / 3) + return(0); + if (vm_page_zero_count >= cnt.v_free_count / 2) + return(0); + #ifdef SMP if (try_mplock()) { #endif s = splvm(); __asm __volatile("sti" : : : "memory"); - m = vm_page_list_find(PQ_FREE, free_rover); - if (m != NULL) { + zero_state = 0; + m = vm_page_list_find(PQ_FREE, free_rover, FALSE); + if (m != NULL && (m->flags & PG_ZERO) == 0) { --(*vm_page_queues[m->queue].lcnt); TAILQ_REMOVE(vm_page_queues[m->queue].pl, m, pageq); m->queue = PQ_NONE; @@ -627,14 +628,17 @@ vm_page_zero_idle() get_mplock(); #endif (void)splvm(); - m->queue = PQ_ZERO + m->pc; + vm_page_flag_set(m, PG_ZERO); + m->queue = PQ_FREE + m->pc; ++(*vm_page_queues[m->queue].lcnt); - TAILQ_INSERT_HEAD(vm_page_queues[m->queue].pl, m, + TAILQ_INSERT_TAIL(vm_page_queues[m->queue].pl, m, pageq); - free_rover = (free_rover + PQ_PRIME3) & PQ_L2_MASK; ++vm_page_zero_count; ++cnt_prezero; + if (vm_page_zero_count >= cnt.v_free_count / 2) + zero_state = 1; } + free_rover = (free_rover + PQ_PRIME3) & PQ_L2_MASK; splx(s); __asm __volatile("cli" : : : "memory"); #ifdef SMP |
