vm: Idlezero changes

* Restore yield to idlezero loop; we lwkt_yield() every 64-bytes rather than
  every page now.
* Unmark as MPSAFE; we are not MPSAFE, we hold the MP lock. When the page
  queues are safe to access with the vm token alone, we can revert to a prior
  edition of this code, which was mpsafe.

diff --git a/sys/vm/vm_zeroidle.c b/sys/vm/vm_zeroidle.c
index ae5ff93..2d286e6 100644 (file)
--- a/sys/vm/vm_zeroidle.c
+++ b/sys/vm/vm_zeroidle.c
@@ -1,6 +1,4 @@
 /*
- * (MPSAFE)
- *
  * Copyright (c) 1994 John Dyson
  * Copyright (c) 2001 Matt Dillon
  * Copyright (c) 2010 The DragonFly Project
@@ -62,7 +60,7 @@
 #define ZIDLE_HI(v)    ((v) * 4 / 5)
 
 /* Number of bytes to zero between reschedule checks */
-#define IDLEZERO_RUN   (32)
+#define IDLEZERO_RUN   (64)
 
 /* Maximum number of pages per second to zero */
 #define NPAGES_RUN     (20000)
@@ -204,8 +202,7 @@ vm_pagezero(void __unused *arg)
                        break;
                case STATE_ZERO_PAGE:
                        /*
-                        * Zero-out the page, stop immediately if a
-                        * resched has been requested.
+                        * Zero-out the page
                         */
                        while (i < PAGE_SIZE) {
                                if (idlezero_nocache == 1)
@@ -213,9 +210,9 @@ vm_pagezero(void __unused *arg)
                                else
                                        bzero(&pg[i], IDLEZERO_RUN);
                                i += IDLEZERO_RUN;
+                               lwkt_yield();
                        }
-                       if (i == PAGE_SIZE)
-                               state = STATE_RELEASE_PAGE;
+                       state = STATE_RELEASE_PAGE;
                        break;
                case STATE_RELEASE_PAGE:
                        lwbuf_free(buf);