svn commit: r337443 - head/sys/vm
Alan Cox
alc at FreeBSD.org
Wed Aug 8 02:30:35 UTC 2018
Author: alc
Date: Wed Aug 8 02:30:34 2018
New Revision: 337443
URL: https://svnweb.freebsd.org/changeset/base/337443
Log:
Defer and aggregate swap_pager_meta_build frees.
Before swp_pager_meta_build replaces an old swapblk with an new one,
it frees the old one. To allow such freeing of blocks to be
aggregated, have swp_pager_meta_build return the old swap block, and
make the caller responsible for freeing it.
Define a pair of short static functions, swp_pager_init_freerange and
swp_pager_update_freerange, to do the initialization and updating of
blk addresses and counters used in aggregating blocks to be freed.
Submitted by: Doug Moore <dougm at rice.edu>
Reviewed by: kib, markj (an earlier version)
Tested by: pho
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D13707
Modified:
head/sys/vm/swap_pager.c
Modified: head/sys/vm/swap_pager.c
==============================================================================
--- head/sys/vm/swap_pager.c Wed Aug 8 01:33:36 2018 (r337442)
+++ head/sys/vm/swap_pager.c Wed Aug 8 02:30:34 2018 (r337443)
@@ -403,11 +403,32 @@ static daddr_t swp_pager_getswapspace(int npages);
/*
* Metadata functions
*/
-static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
+static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t);
static void swp_pager_meta_free_all(vm_object_t);
static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int);
+static void
+swp_pager_init_freerange(daddr_t *start, daddr_t *num)
+{
+
+ *start = SWAPBLK_NONE;
+ *num = 0;
+}
+
+static void
+swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr)
+{
+
+ if (*start + *num == addr) {
+ (*num)++;
+ } else {
+ swp_pager_freeswapspace(*start, *num);
+ *start = addr;
+ *num = 1;
+ }
+}
+
static void *
swblk_trie_alloc(struct pctrie *ptree)
{
@@ -861,7 +882,9 @@ swap_pager_reserve(vm_object_t object, vm_pindex_t sta
int n = 0;
daddr_t blk = SWAPBLK_NONE;
vm_pindex_t beg = start; /* save start index */
+ daddr_t addr, n_free, s_free;
+ swp_pager_init_freerange(&s_free, &n_free);
VM_OBJECT_WLOCK(object);
while (size) {
if (n == 0) {
@@ -875,12 +898,15 @@ swap_pager_reserve(vm_object_t object, vm_pindex_t sta
}
}
}
- swp_pager_meta_build(object, start, blk);
+ addr = swp_pager_meta_build(object, start, blk);
+ if (addr != SWAPBLK_NONE)
+ swp_pager_update_freerange(&s_free, &n_free, addr);
--size;
++start;
++blk;
--n;
}
+ swp_pager_freeswapspace(s_free, n_free);
swp_pager_meta_free(object, start, n);
VM_OBJECT_WUNLOCK(object);
return (0);
@@ -910,7 +936,7 @@ swap_pager_copy(vm_object_t srcobject, vm_object_t dst
vm_pindex_t offset, int destroysource)
{
vm_pindex_t i;
- daddr_t dstaddr, first_free, num_free, srcaddr;
+ daddr_t dstaddr, n_free, s_free, srcaddr;
VM_OBJECT_ASSERT_WLOCKED(srcobject);
VM_OBJECT_ASSERT_WLOCKED(dstobject);
@@ -937,42 +963,38 @@ swap_pager_copy(vm_object_t srcobject, vm_object_t dst
/*
* Transfer source to destination.
*/
- first_free = SWAPBLK_NONE;
- num_free = 0;
+ swp_pager_init_freerange(&s_free, &n_free);
for (i = 0; i < dstobject->size; ++i) {
srcaddr = swp_pager_meta_ctl(srcobject, i + offset, SWM_POP);
if (srcaddr == SWAPBLK_NONE)
continue;
dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
- if (dstaddr == SWAPBLK_NONE) {
+ if (dstaddr != SWAPBLK_NONE) {
/*
- * Destination has no swapblk and is not resident,
- * copy source.
- *
- * swp_pager_meta_build() can sleep.
- */
- vm_object_pip_add(srcobject, 1);
- VM_OBJECT_WUNLOCK(srcobject);
- vm_object_pip_add(dstobject, 1);
- swp_pager_meta_build(dstobject, i, srcaddr);
- vm_object_pip_wakeup(dstobject);
- VM_OBJECT_WLOCK(srcobject);
- vm_object_pip_wakeup(srcobject);
- } else {
- /*
* Destination has valid swapblk or it is represented
- * by a resident page. We destroy the sourceblock.
+ * by a resident page. We destroy the source block.
*/
- if (first_free + num_free == srcaddr)
- num_free++;
- else {
- swp_pager_freeswapspace(first_free, num_free);
- first_free = srcaddr;
- num_free = 1;
- }
+ swp_pager_update_freerange(&s_free, &n_free, srcaddr);
+ continue;
}
+
+ /*
+ * Destination has no swapblk and is not resident,
+ * copy source.
+ *
+ * swp_pager_meta_build() can sleep.
+ */
+ vm_object_pip_add(srcobject, 1);
+ VM_OBJECT_WUNLOCK(srcobject);
+ vm_object_pip_add(dstobject, 1);
+ dstaddr = swp_pager_meta_build(dstobject, i, srcaddr);
+ KASSERT(dstaddr == SWAPBLK_NONE,
+ ("Unexpected destination swapblk"));
+ vm_object_pip_wakeup(dstobject);
+ VM_OBJECT_WLOCK(srcobject);
+ vm_object_pip_wakeup(srcobject);
}
- swp_pager_freeswapspace(first_free, num_free);
+ swp_pager_freeswapspace(s_free, n_free);
/*
* Free left over swap blocks in source.
@@ -1307,7 +1329,9 @@ swap_pager_putpages(vm_object_t object, vm_page_t *ma,
{
int i, n;
boolean_t sync;
+ daddr_t addr, n_free, s_free;
+ swp_pager_init_freerange(&s_free, &n_free);
if (count && ma[0]->object != object) {
panic("swap_pager_putpages: object mismatch %p/%p",
object,
@@ -1322,8 +1346,11 @@ swap_pager_putpages(vm_object_t object, vm_page_t *ma,
* check for bogus sysops
* force sync if not pageout process
*/
- if (object->type != OBJT_SWAP)
- swp_pager_meta_build(object, 0, SWAPBLK_NONE);
+ if (object->type != OBJT_SWAP) {
+ addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE);
+ KASSERT(addr == SWAPBLK_NONE,
+ ("unexpected object swap block"));
+ }
VM_OBJECT_WUNLOCK(object);
n = 0;
@@ -1391,11 +1418,11 @@ swap_pager_putpages(vm_object_t object, vm_page_t *ma,
for (j = 0; j < n; ++j) {
vm_page_t mreq = ma[i+j];
- swp_pager_meta_build(
- mreq->object,
- mreq->pindex,
- blk + j
- );
+ addr = swp_pager_meta_build(mreq->object, mreq->pindex,
+ blk + j);
+ if (addr != SWAPBLK_NONE)
+ swp_pager_update_freerange(&s_free, &n_free,
+ addr);
MPASS(mreq->dirty == VM_PAGE_BITS_ALL);
mreq->oflags |= VPO_SWAPINPROG;
bp->b_pages[j] = mreq;
@@ -1453,6 +1480,7 @@ swap_pager_putpages(vm_object_t object, vm_page_t *ma,
swp_pager_async_iodone(bp);
}
VM_OBJECT_WLOCK(object);
+ swp_pager_freeswapspace(s_free, n_free);
}
/*
@@ -1783,14 +1811,15 @@ swp_pager_swblk_empty(struct swblk *sb, int start, int
*
* 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.
+ * assigned swapblk is returned.
*/
-static void
+static daddr_t
swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
{
static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted;
struct swblk *sb, *sb1;
vm_pindex_t modpi, rdpi;
+ daddr_t prev_swapblk;
int error, i;
VM_OBJECT_ASSERT_WLOCKED(object);
@@ -1815,7 +1844,7 @@ swp_pager_meta_build(vm_object_t object, vm_pindex_t p
sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi);
if (sb == NULL) {
if (swapblk == SWAPBLK_NONE)
- return;
+ return (SWAPBLK_NONE);
for (;;) {
sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc ==
pageproc ? M_USE_RESERVE : 0));
@@ -1882,9 +1911,8 @@ allocated:
MPASS(sb->p == rdpi);
modpi = pindex % SWAP_META_PAGES;
- /* Delete prior contents of metadata. */
- if (sb->d[modpi] != SWAPBLK_NONE)
- swp_pager_freeswapspace(sb->d[modpi], 1);
+ /* Return prior contents of metadata. */
+ prev_swapblk = sb->d[modpi];
/* Enter block into metadata. */
sb->d[modpi] = swapblk;
@@ -1896,6 +1924,7 @@ allocated:
SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, rdpi);
uma_zfree(swblk_zone, sb);
}
+ return (prev_swapblk);
}
/*
@@ -1912,7 +1941,7 @@ static void
swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count)
{
struct swblk *sb;
- daddr_t first_free, num_free;
+ daddr_t n_free, s_free;
vm_pindex_t last;
int i, limit, start;
@@ -1920,8 +1949,7 @@ swp_pager_meta_free(vm_object_t object, vm_pindex_t pi
if (object->type != OBJT_SWAP || count == 0)
return;
- first_free = SWAPBLK_NONE;
- num_free = 0;
+ swp_pager_init_freerange(&s_free, &n_free);
last = pindex + count;
for (;;) {
sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks,
@@ -1934,13 +1962,7 @@ swp_pager_meta_free(vm_object_t object, vm_pindex_t pi
for (i = start; i < limit; i++) {
if (sb->d[i] == SWAPBLK_NONE)
continue;
- if (first_free + num_free == sb->d[i])
- num_free++;
- else {
- swp_pager_freeswapspace(first_free, num_free);
- first_free = sb->d[i];
- num_free = 1;
- }
+ swp_pager_update_freerange(&s_free, &n_free, sb->d[i]);
sb->d[i] = SWAPBLK_NONE;
}
if (swp_pager_swblk_empty(sb, 0, start) &&
@@ -1951,7 +1973,7 @@ swp_pager_meta_free(vm_object_t object, vm_pindex_t pi
}
pindex = sb->p + SWAP_META_PAGES;
}
- swp_pager_freeswapspace(first_free, num_free);
+ swp_pager_freeswapspace(s_free, n_free);
}
/*
@@ -1964,7 +1986,7 @@ static void
swp_pager_meta_free_all(vm_object_t object)
{
struct swblk *sb;
- daddr_t first_free, num_free;
+ daddr_t n_free, s_free;
vm_pindex_t pindex;
int i;
@@ -1972,26 +1994,19 @@ swp_pager_meta_free_all(vm_object_t object)
if (object->type != OBJT_SWAP)
return;
- first_free = SWAPBLK_NONE;
- num_free = 0;
+ swp_pager_init_freerange(&s_free, &n_free);
for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE(
&object->un_pager.swp.swp_blks, pindex)) != NULL;) {
pindex = sb->p + SWAP_META_PAGES;
for (i = 0; i < SWAP_META_PAGES; i++) {
if (sb->d[i] == SWAPBLK_NONE)
continue;
- if (first_free + num_free == sb->d[i])
- num_free++;
- else {
- swp_pager_freeswapspace(first_free, num_free);
- first_free = sb->d[i];
- num_free = 1;
- }
+ swp_pager_update_freerange(&s_free, &n_free, sb->d[i]);
}
SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p);
uma_zfree(swblk_zone, sb);
}
- swp_pager_freeswapspace(first_free, num_free);
+ swp_pager_freeswapspace(s_free, n_free);
}
/*
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