Author: kib
Date: Mon Aug 29 10:29:05 2011
New Revision: 225244
URL: http://svn.freebsd.org/changeset/base/225244
Log:
MFC r221096 (by obrien):
Reap old SPL comments.
MFC r225089:
Update some comments in swap_pager.c.
Modified:
stable/8/sys/vm/swap_pager.c
Directory Properties:
stable/8/sys/ (props changed)
stable/8/sys/amd64/include/xen/ (props changed)
stable/8/sys/cddl/contrib/opensolaris/ (props changed)
stable/8/sys/contrib/dev/acpica/ (props changed)
stable/8/sys/contrib/pf/ (props changed)
Modified: stable/8/sys/vm/swap_pager.c
==============================================================================
--- stable/8/sys/vm/swap_pager.c Mon Aug 29 10:15:15 2011
(r225243)
+++ stable/8/sys/vm/swap_pager.c Mon Aug 29 10:29:05 2011
(r225244)
@@ -113,9 +113,9 @@ __FBSDID("$FreeBSD$");
#include <geom/geom.h>
/*
- * SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, or 16
- * pages per allocation. We recommend you stick with the default of 8.
- * The 16-page limit is due to the radix code (kern/subr_blist.c).
+ * SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, 16
+ * or 32 pages per allocation.
+ * The 32-page limit is due to the radix code (kern/subr_blist.c).
*/
#ifndef MAX_PAGEOUT_CLUSTER
#define MAX_PAGEOUT_CLUSTER 16
@@ -126,14 +126,11 @@ __FBSDID("$FreeBSD$");
#endif
/*
- * Piecemeal swap metadata structure. Swap is stored in a radix tree.
- *
- * If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix
- * is basically 8. Assuming PAGE_SIZE == 4096, one tree level represents
- * 32K worth of data, two levels represent 256K, three levels represent
- * 2 MBytes. This is acceptable.
- *
- * Overall memory utilization is about the same as the old swap structure.
+ * The swblock structure maps an object and a small, fixed-size range
+ * of page indices to disk addresses within a swap area.
+ * The collection of these mappings is implemented as a hash table.
+ * Unused disk addresses within a swap area are allocated and managed
+ * using a blist.
*/
#define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
#define SWAP_META_PAGES (SWB_NPAGES * 2)
@@ -392,7 +389,6 @@ swp_pager_free_nrpage(vm_page_t m)
*
* No restrictions on call
* This routine may not block.
- * This routine must be called at splvm()
*/
static void
swp_sizecheck(void)
@@ -417,8 +413,6 @@ swp_sizecheck(void)
* the object and page index. It returns a pointer to a pointer
* to the object, or a pointer to a NULL pointer if it could not
* find a swapblk.
- *
- * This routine must be called at splvm().
*/
static struct swblock **
swp_pager_hash(vm_object_t object, vm_pindex_t index)
@@ -558,12 +552,7 @@ swap_pager_swap_init(void)
* and then converting it with swp_pager_meta_build().
*
* This routine may block in vm_object_allocate() and create a named
- * object lookup race, so we must interlock. We must also run at
- * splvm() for the object lookup to handle races with interrupts, but
- * we do not have to maintain splvm() in between the lookup and the
- * add because (I believe) it is not possible to attempt to create
- * a new swap object w/handle when a default object with that handle
- * already exists.
+ * object lookup race, so we must interlock.
*
* MPSAFE
*/
@@ -636,9 +625,7 @@ swap_pager_alloc(void *handle, vm_ooffse
* routine is typically called only when the entire object is
* about to be destroyed.
*
- * This routine may block, but no longer does.
- *
- * The object must be locked or unreferenceable.
+ * The object must be locked.
*/
static void
swap_pager_dealloc(vm_object_t object)
@@ -680,11 +667,7 @@ swap_pager_dealloc(vm_object_t object)
* Also has the side effect of advising that somebody made a mistake
* when they configured swap and didn't configure enough.
*
- * Must be called at splvm() to avoid races with bitmap frees from
- * vm_page_remove() aka swap_pager_page_removed().
- *
- * This routine may not block
- * This routine must be called at splvm().
+ * This routine may not sleep.
*
* We allocate in round-robin fashion from the configured devices.
*/
@@ -754,14 +737,7 @@ swp_pager_strategy(struct buf *bp)
*
* This routine returns the specified swap blocks back to the bitmap.
*
- * Note: This routine may not block (it could in the old swap code),
- * and through the use of the new blist routines it does not block.
- *
- * We must be called at splvm() to avoid races with bitmap frees from
- * vm_page_remove() aka swap_pager_page_removed().
- *
- * This routine may not block
- * This routine must be called at splvm().
+ * This routine may not sleep.
*/
static void
swp_pager_freeswapspace(daddr_t blk, int npages)
@@ -801,9 +777,6 @@ swp_pager_freeswapspace(daddr_t blk, int
* The external callers of this routine typically have already destroyed
* or renamed vm_page_t's associated with this range in the object so
* we should be ok.
- *
- * This routine may be called at any spl. We up our spl to splvm
temporarily
- * in order to perform the metadata removal.
*/
void
swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size)
@@ -860,23 +833,16 @@ swap_pager_reserve(vm_object_t object, v
* cases where both the source and destination have a valid swapblk,
* we keep the destination's.
*
- * This routine is allowed to block. It may block allocating metadata
+ * This routine is allowed to sleep. It may sleep allocating metadata
* indirectly through swp_pager_meta_build() or if paging is still in
* progress on the source.
*
- * This routine can be called at any spl
- *
- * XXX vm_page_collapse() kinda expects us not to block because we
- * supposedly do not need to allocate memory, but for the moment we
- * *may* have to get a little memory from the zone allocator, but
- * it is taken from the interrupt memory. We should be ok.
- *
* The source object contains no vm_page_t's (which is just as well)
*
* The source object is of type OBJT_SWAP.
*
- * The source and destination objects must be locked or
- * inaccessible (XXX are they ?)
+ * The source and destination objects must be locked.
+ * Both object locks may temporarily be released.
*/
void
swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
@@ -1053,8 +1019,7 @@ swap_pager_haspage(vm_object_t object, v
* does NOT change the m->dirty status of the page. Also: MADV_FREE
* depends on it.
*
- * This routine may not block
- * This routine must be called at splvm()
+ * This routine may not sleep.
*/
static void
swap_pager_unswapped(vm_page_t m)
@@ -1462,7 +1427,7 @@ swap_pager_putpages(vm_object_t object,
* operations, we vm_page_t->busy'd unbusy all pages ( we can do this
* because we marked them all VM_PAGER_PEND on return from putpages ).
*
- * This routine may not block.
+ * This routine may not sleep.
*/
static void
swp_pager_async_iodone(struct buf *bp)
@@ -1642,7 +1607,7 @@ swp_pager_async_iodone(struct buf *bp)
* Return 1 if at least one page in the given object is paged
* out to the given swap device.
*
- * This routine may not block.
+ * This routine may not sleep.
*/
int
swap_pager_isswapped(vm_object_t object, struct swdevt *sp)
@@ -1782,9 +1747,7 @@ restart:
************************************************************************
*
* These routines manipulate the swap metadata stored in the
- * OBJT_SWAP object. All swp_*() routines must be called at
- * splvm() because swap can be freed up by the low level vm_page
- * code which might be called from interrupts beyond what splbio() covers.
+ * OBJT_SWAP object.
*
* Swap metadata is implemented with a global hash and not directly
* linked into the object. Instead the object simply contains
@@ -1800,9 +1763,6 @@ restart:
* The specified swapblk is added to the object's swap metadata. If
* the swapblk is not valid, it is freed instead. Any previously
* assigned swapblk is freed.
- *
- * This routine must be called at splvm(), except when used to convert
- * an OBJT_DEFAULT object into an OBJT_SWAP object.
*/
static void
swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
@@ -1899,8 +1859,6 @@ done:
* This routine will free swap metadata structures as they are cleaned
* out. This routine does *NOT* operate on swap metadata associated
* with resident pages.
- *
- * This routine must be called at splvm()
*/
static void
swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count)
@@ -1946,8 +1904,6 @@ swp_pager_meta_free(vm_object_t object,
*
* This routine locates and destroys all swap metadata associated with
* an object.
- *
- * This routine must be called at splvm()
*/
static void
swp_pager_meta_free_all(vm_object_t object)
@@ -2002,8 +1958,6 @@ swp_pager_meta_free_all(vm_object_t obje
* have to wait until paging is complete but otherwise can act on the
* busy page.
*
- * This routine must be called at splvm().
- *
* SWM_FREE remove and free swap block from metadata
* SWM_POP remove from meta data but do not free.. pop it out
*/
_______________________________________________
svn-src-all@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
