You can apply my previous patch on 2.6.20 by changing
-#define VM_PURE_PRIVATE 0x04000000 /* Is the vma is only belonging to a mm,
to
+#define VM_PURE_PRIVATE 0x08000000 /* Is the vma is only belonging to a mm,
New revision is based on 2.6.20 with my previous patch, major changelogs are
1) pte_unmap pairs on shrink_pvma_scan_ptes and pps_swapoff_scan_ptes.
2) Now, kppsd can be woke up by kswapd.
3) New global variable accelerate_kppsd is appended to accelerate the
reclamation process when a memory inode is low.
Signed-off-by: Yunfeng Zhang <[email protected]>
Index: linux-2.6.19/Documentation/vm_pps.txt
===================================================================
--- linux-2.6.19.orig/Documentation/vm_pps.txt 2007-02-12
12:45:07.000000000 +0800
+++ linux-2.6.19/Documentation/vm_pps.txt 2007-02-12 15:30:16.490797672 +0800
@@ -143,23 +143,32 @@
2) mm/memory.c do_wp_page, handle_pte_fault::unmapped_pte, do_anonymous_page,
do_swap_page (page-fault)
3) mm/memory.c get_user_pages (sometimes core need share PrivatePage with us)
+4) mm/vmscan.c balance_pgdat (kswapd/x can do stage 5 of its node pages,
+ while kppsd can do stage 1-4)
+5) mm/vmscan.c kppsd (new core daemon -- kppsd, see below)
There isn't new lock order defined in pps, that is, it's compliable to Linux
-lock order.
+lock order. Locks in shrink_private_vma copied from shrink_list of 2.6.16.29
+(my initial version).
// }])>
// Others about pps <([{
A new kernel thread -- kppsd is introduced in mm/vmscan.c, its task is to
-execute the stages of pps periodically, note an appropriate timeout ticks is
-necessary so we can give application a chance to re-map back its PrivatePage
-from UnmappedPTE to PTE, that is, show their conglomeration affinity.
-
-kppsd can be controlled by new fields -- scan_control::may_reclaim/reclaim_node
-may_reclaim = 1 means starting reclamation (stage 5). reclaim_node = (node
-number) is used when a memory node is low. Caller should set them to wakeup_sc,
-then wake up kppsd (vmscan.c:balance_pgdat). Note, if kppsd is started due to
-timeout, it doesn't do stage 5 at all (vmscan.c:kppsd). Other alive legacy
-fields are gfp_mask, may_writepage and may_swap.
+execute the stage 1 - 4 of pps periodically, note an appropriate timeout ticks
+(current 2 seconds) is necessary so we can give application a chance to re-map
+back its PrivatePage from UnmappedPTE to PTE, that is, show their
+conglomeration affinity.
+
+shrink_private_vma can be controlled by new fields -- may_reclaim, reclaim_node
+and is_kppsd of scan_control. may_reclaim = 1 means starting reclamation
+(stage 5). reclaim_node = (node number, -1 means all memory inode) is used when
+a memory node is low. Caller (kswapd/x), typically, set reclaim_node to start
+shrink_private_vma (vmscan.c:balance_pgdat). Note, only to kppsd is_kppsd = 1.
+Other alive legacy fields to pps are gfp_mask, may_writepage and may_swap.
+
+When a memory inode is low, kswapd/x can wake up kppsd by increasing global
+variable accelerate_kppsd (balance_pgdat), which accelerate stage 1 - 4, and
+call shrink_private_vma to do stage 5.
PPS statistic data is appended to /proc/meminfo entry, its prototype is in
include/linux/mm.h.
Index: linux-2.6.19/mm/swapfile.c
===================================================================
--- linux-2.6.19.orig/mm/swapfile.c 2007-02-12 12:45:07.000000000 +0800
+++ linux-2.6.19/mm/swapfile.c 2007-02-12 12:45:21.000000000 +0800
@@ -569,6 +569,7 @@
}
}
} while (pte++, addr += PAGE_SIZE, addr != end);
+ pte_unmap(pte);
return 0;
}
Index: linux-2.6.19/mm/vmscan.c
===================================================================
--- linux-2.6.19.orig/mm/vmscan.c 2007-02-12 12:45:07.000000000 +0800
+++ linux-2.6.19/mm/vmscan.c 2007-02-12 15:48:59.217292888 +0800
@@ -70,6 +70,7 @@
/* pps control command. See Documentation/vm_pps.txt. */
int may_reclaim;
int reclaim_node;
+ int is_kppsd;
};
/*
@@ -1101,9 +1102,9 @@
return ret;
}
-// pps fields.
+// pps fields, see Documentation/vm_pps.txt.
static wait_queue_head_t kppsd_wait;
-static struct scan_control wakeup_sc;
+static int accelerate_kppsd = 0;
struct pps_info pps_info = {
.total = ATOMIC_INIT(0),
.pte_count = ATOMIC_INIT(0), // stage 1 and 2.
@@ -1118,24 +1119,22 @@
struct page* pages[MAX_SERIES_LENGTH];
int series_length;
int series_stage;
-} series;
+};
-static int get_series_stage(pte_t* pte, int index)
+static int get_series_stage(struct series_t* series, pte_t* pte, int index)
{
- series.orig_ptes[index] = *pte;
- series.ptes[index] = pte;
- if (pte_present(series.orig_ptes[index])) {
- struct page* page = pfn_to_page(pte_pfn(series.orig_ptes[index]));
- series.pages[index] = page;
+ series->orig_ptes[index] = *pte;
+ series->ptes[index] = pte;
+ struct page* page = pfn_to_page(pte_pfn(series->orig_ptes[index]));
+ series->pages[index] = page;
+ if (pte_present(series->orig_ptes[index])) {
if (page == ZERO_PAGE(addr)) // reserved page is exclusive from us.
return 7;
- if (pte_young(series.orig_ptes[index])) {
+ if (pte_young(series->orig_ptes[index])) {
return 1;
} else
return 2;
- } else if (pte_unmapped(series.orig_ptes[index])) {
- struct page* page = pfn_to_page(pte_pfn(series.orig_ptes[index]));
- series.pages[index] = page;
+ } else if (pte_unmapped(series->orig_ptes[index])) {
if (!PageSwapCache(page))
return 3;
else {
@@ -1148,19 +1147,20 @@
return 6;
}
-static void find_series(pte_t** start, unsigned long* addr, unsigned long end)
+static void find_series(struct series_t* series, pte_t** start, unsigned long*
+ addr, unsigned long end)
{
int i;
- int series_stage = get_series_stage((*start)++, 0);
+ int series_stage = get_series_stage(series, (*start)++, 0);
*addr += PAGE_SIZE;
for (i = 1; i < MAX_SERIES_LENGTH && *addr < end; i++, (*start)++,
*addr += PAGE_SIZE) {
- if (series_stage != get_series_stage(*start, i))
+ if (series_stage != get_series_stage(series, *start, i))
break;
}
- series.series_stage = series_stage;
- series.series_length = i;
+ series->series_stage = series_stage;
+ series->series_length = i;
}
struct delay_tlb_task delay_tlb_tasks[32] = { [0 ... 31] = {0} };
@@ -1284,9 +1284,9 @@
goto fill_it;
}
-static void shrink_pvma_scan_ptes(struct scan_control* sc, struct mm_struct*
- mm, struct vm_area_struct* vma, pmd_t* pmd, unsigned long addr,
- unsigned long end)
+static unsigned long shrink_pvma_scan_ptes(struct scan_control* sc, struct
+ mm_struct* mm, struct vm_area_struct* vma, pmd_t* pmd, unsigned
+ long addr, unsigned long end)
{
int i, statistic;
spinlock_t* ptl = pte_lockptr(mm, pmd);
@@ -1295,32 +1295,43 @@
struct pagevec freed_pvec;
int may_enter_fs = (sc->gfp_mask & (__GFP_FS | __GFP_IO));
struct address_space* mapping = &swapper_space;
+ unsigned long nr_reclaimed = 0;
+ struct series_t series;
pagevec_init(&freed_pvec, 1);
do {
memset(&series, 0, sizeof(struct series_t));
- find_series(&pte, &addr, end);
+ find_series(&series, &pte, &addr, end);
if (sc->may_reclaim == 0 && series.series_stage == 5)
continue;
+ if (!sc->is_kppsd && series.series_stage != 5)
+ continue;
switch (series.series_stage) {
case 1: // PTE -- untouched PTE.
for (i = 0; i < series.series_length; i++) {
struct page* page = series.pages[i];
- lock_page(page);
+ if (TestSetPageLocked(page))
+ continue;
spin_lock(ptl);
- if (unlikely(pte_same(*series.ptes[i],
- series.orig_ptes[i]))) {
- if (pte_dirty(*series.ptes[i]))
- set_page_dirty(page);
- set_pte_at(mm, addr + i * PAGE_SIZE,
- series.ptes[i],
- pte_mkold(pte_mkclean(*series.ptes[i])));
+ // To get dirty bit from pte safely, using the idea of
+ // dftlb of stage 2.
+ pte_t pte_new = series.orig_ptes[i];
+ pte_new = pte_mkold(pte_mkclean(series.orig_ptes[i]));
+ if (cmpxchg(&series.ptes[i]->pte_low,
+ series.orig_ptes[i].pte_low,
+ pte_new.pte_low) !=
+ series.orig_ptes[i].pte_low) {
+ spin_unlock(ptl);
+ unlock_page(page);
+ continue;
}
+ if (pte_dirty(series.orig_ptes[i]))
+ set_page_dirty(page);
spin_unlock(ptl);
unlock_page(page);
}
fill_in_tlb_tasks(vma, addr, addr + (PAGE_SIZE *
- series.series_length));
+ series.series_length));
break;
case 2: // untouched PTE -- UnmappedPTE.
/*
@@ -1335,37 +1346,39 @@
spin_lock(ptl);
statistic = 0;
for (i = 0; i < series.series_length; i++) {
- if (unlikely(pte_same(*series.ptes[i],
- series.orig_ptes[i]))) {
- pte_t pte_unmapped = series.orig_ptes[i];
- pte_unmapped.pte_low &= ~_PAGE_PRESENT;
- pte_unmapped.pte_low |= _PAGE_UNMAPPED;
- if (cmpxchg(&series.ptes[i]->pte_low,
- series.orig_ptes[i].pte_low,
- pte_unmapped.pte_low) !=
- series.orig_ptes[i].pte_low)
- continue;
- page_remove_rmap(series.pages[i], vma);
- anon_rss--;
- statistic++;
- }
+ pte_t pte_unmapped = series.orig_ptes[i];
+ pte_unmapped.pte_low &= ~_PAGE_PRESENT;
+ pte_unmapped.pte_low |= _PAGE_UNMAPPED;
+ if (cmpxchg(&series.ptes[i]->pte_low,
+ series.orig_ptes[i].pte_low,
+ pte_unmapped.pte_low) !=
+ series.orig_ptes[i].pte_low)
+ continue;
+ page_remove_rmap(series.pages[i], vma);
+ anon_rss--;
+ statistic++;
}
atomic_add(statistic, &pps_info.unmapped_count);
atomic_sub(statistic, &pps_info.pte_count);
spin_unlock(ptl);
- break;
+ if (!accelerate_kppsd)
+ break;
case 3: // Attach SwapPage to PrivatePage.
/*
* A better arithmetic should be applied to Linux SwapDevice to
* allocate fake continual SwapPages which are close to each
* other, the offset between two close SwapPages is less than 8.
+ *
+ * We can re-allocate SwapPages here if process private pages
+ * are pure private.
*/
if (sc->may_swap) {
for (i = 0; i < series.series_length; i++) {
- lock_page(series.pages[i]);
+ if (TestSetPageLocked(series.pages[i]))
+ continue;
if (!PageSwapCache(series.pages[i])) {
if (!add_to_swap(series.pages[i],
- GFP_ATOMIC)) {
+ GFP_ATOMIC)) {
unlock_page(series.pages[i]);
break;
}
@@ -1373,45 +1386,49 @@
unlock_page(series.pages[i]);
}
}
- break;
+ if (!accelerate_kppsd)
+ break;
case 4: // SwapPage isn't consistent with PrivatePage.
/*
* A mini version pageout().
*
* Current swap space can't commit multiple pages together:(
*/
- if (sc->may_writepage && may_enter_fs) {
- for (i = 0; i < series.series_length; i++) {
- struct page* page = series.pages[i];
- int res;
+ if (!(sc->may_writepage && may_enter_fs))
+ break;
+ for (i = 0; i < series.series_length; i++) {
+ struct page* page = series.pages[i];
+ int res;
- if (!may_write_to_queue(mapping->backing_dev_info))
- break;
- lock_page(page);
- if (!PageDirty(page) || PageWriteback(page)) {
- unlock_page(page);
- continue;
- }
- clear_page_dirty_for_io(page);
- struct writeback_control wbc = {
- .sync_mode = WB_SYNC_NONE,
- .nr_to_write = SWAP_CLUSTER_MAX,
- .nonblocking = 1,
- .for_reclaim = 1,
- };
- page_cache_get(page);
- SetPageReclaim(page);
- res = swap_writepage(page, &wbc);
- if (res < 0) {
- handle_write_error(mapping, page, res);
- ClearPageReclaim(page);
- page_cache_release(page);
- break;
- }
- if (!PageWriteback(page))
- ClearPageReclaim(page);
+ if (!may_write_to_queue(mapping->backing_dev_info))
+ break;
+ if (TestSetPageLocked(page))
+ continue;
+ if (!PageDirty(page) || PageWriteback(page)) {
+ unlock_page(page);
+ continue;
+ }
+ clear_page_dirty_for_io(page);
+ struct writeback_control wbc = {
+ .sync_mode = WB_SYNC_NONE,
+ .nr_to_write = SWAP_CLUSTER_MAX,
+ .range_start = 0,
+ .range_end = LLONG_MAX,
+ .nonblocking = 1,
+ .for_reclaim = 1,
+ };
+ page_cache_get(page);
+ SetPageReclaim(page);
+ res = swap_writepage(page, &wbc);
+ if (res < 0) {
+ handle_write_error(mapping, page, res);
+ ClearPageReclaim(page);
page_cache_release(page);
+ break;
}
+ if (!PageWriteback(page))
+ ClearPageReclaim(page);
+ page_cache_release(page);
}
break;
case 5: // UnmappedPTE -- SwappedPTE, reclaim PrivatePage.
@@ -1419,10 +1436,11 @@
for (i = 0; i < series.series_length; i++) {
struct page* page = series.pages[i];
if (!(page_to_nid(page) == sc->reclaim_node ||
- sc->reclaim_node == -1))
+ sc->reclaim_node == -1))
continue;
- lock_page(page);
+ if (TestSetPageLocked(page))
+ continue;
spin_lock(ptl);
if (!pte_same(*series.ptes[i], series.orig_ptes[i]) ||
/* We're racing with get_user_pages. */
@@ -1449,6 +1467,7 @@
atomic_add(statistic, &pps_info.swapped_count);
atomic_sub(statistic, &pps_info.unmapped_count);
atomic_sub(statistic, &pps_info.total);
+ nr_reclaimed += statistic;
break;
case 6:
// NULL operation!
@@ -1456,58 +1475,67 @@
}
} while (addr < end);
add_mm_counter(mm, anon_rss, anon_rss);
+ pte_unmap(pte);
if (pagevec_count(&freed_pvec))
__pagevec_release_nonlru(&freed_pvec);
+ return nr_reclaimed;
}
-static void shrink_pvma_pmd_range(struct scan_control* sc, struct mm_struct*
- mm, struct vm_area_struct* vma, pud_t* pud, unsigned long addr,
- unsigned long end)
+static unsigned long shrink_pvma_pmd_range(struct scan_control* sc, struct
+ mm_struct* mm, struct vm_area_struct* vma, pud_t* pud, unsigned
+ long addr, unsigned long end)
{
unsigned long next;
+ unsigned long nr_reclaimed = 0;
pmd_t* pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
- shrink_pvma_scan_ptes(sc, mm, vma, pmd, addr, next);
+ nr_reclaimed += shrink_pvma_scan_ptes(sc, mm, vma, pmd, addr, next);
} while (pmd++, addr = next, addr != end);
+ return nr_reclaimed;
}
-static void shrink_pvma_pud_range(struct scan_control* sc, struct mm_struct*
- mm, struct vm_area_struct* vma, pgd_t* pgd, unsigned long addr,
- unsigned long end)
+static unsigned long shrink_pvma_pud_range(struct scan_control* sc, struct
+ mm_struct* mm, struct vm_area_struct* vma, pgd_t* pgd, unsigned
+ long addr, unsigned long end)
{
unsigned long next;
+ unsigned long nr_reclaimed = 0;
pud_t* pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
- shrink_pvma_pmd_range(sc, mm, vma, pud, addr, next);
+ nr_reclaimed += shrink_pvma_pmd_range(sc, mm, vma, pud, addr, next);
} while (pud++, addr = next, addr != end);
+ return nr_reclaimed;
}
-static void shrink_pvma_pgd_range(struct scan_control* sc, struct mm_struct*
- mm, struct vm_area_struct* vma)
+static unsigned long shrink_pvma_pgd_range(struct scan_control* sc, struct
+ mm_struct* mm, struct vm_area_struct* vma)
{
unsigned long next;
unsigned long addr = vma->vm_start;
unsigned long end = vma->vm_end;
+ unsigned long nr_reclaimed = 0;
pgd_t* pgd = pgd_offset(mm, addr);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
- shrink_pvma_pud_range(sc, mm, vma, pgd, addr, next);
+ nr_reclaimed += shrink_pvma_pud_range(sc, mm, vma, pgd, addr, next);
} while (pgd++, addr = next, addr != end);
+ return nr_reclaimed;
}
-static void shrink_private_vma(struct scan_control* sc)
+static unsigned long shrink_private_vma(struct scan_control* sc)
{
struct vm_area_struct* vma;
struct list_head *pos;
struct mm_struct *prev, *mm;
+ unsigned long nr_reclaimed = 0;
prev = mm = &init_mm;
pos = &init_mm.mmlist;
@@ -1520,22 +1548,25 @@
spin_unlock(&mmlist_lock);
mmput(prev);
prev = mm;
- start_tlb_tasks(mm);
+ if (sc->is_kppsd)
+ start_tlb_tasks(mm);
if (down_read_trylock(&mm->mmap_sem)) {
for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
if (!(vma->vm_flags & VM_PURE_PRIVATE))
continue;
if (vma->vm_flags & VM_LOCKED)
continue;
- shrink_pvma_pgd_range(sc, mm, vma);
+ nr_reclaimed += shrink_pvma_pgd_range(sc, mm, vma);
}
up_read(&mm->mmap_sem);
}
- end_tlb_tasks();
+ if (sc->is_kppsd)
+ end_tlb_tasks();
spin_lock(&mmlist_lock);
}
spin_unlock(&mmlist_lock);
mmput(prev);
+ return nr_reclaimed;
}
/*
@@ -1585,10 +1616,12 @@
sc.may_writepage = !laptop_mode;
count_vm_event(PAGEOUTRUN);
- wakeup_sc = sc;
- wakeup_sc.may_reclaim = 1;
- wakeup_sc.reclaim_node = pgdat->node_id;
- wake_up_interruptible(&kppsd_wait);
+ accelerate_kppsd++;
+ wake_up(&kppsd_wait);
+ sc.may_reclaim = 1;
+ sc.reclaim_node = pgdat->node_id;
+ sc.is_kppsd = 0;
+ nr_reclaimed += shrink_private_vma(&sc);
for (i = 0; i < pgdat->nr_zones; i++)
temp_priority[i] = DEF_PRIORITY;
@@ -2173,26 +2206,24 @@
static int kppsd(void* p)
{
struct task_struct *tsk = current;
- int timeout;
DEFINE_WAIT(wait);
tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE;
struct scan_control default_sc;
default_sc.gfp_mask = GFP_KERNEL;
- default_sc.may_writepage = 1;
default_sc.may_swap = 1;
default_sc.may_reclaim = 0;
default_sc.reclaim_node = -1;
+ default_sc.is_kppsd = 1;
while (1) {
try_to_freeze();
- prepare_to_wait(&kppsd_wait, &wait, TASK_INTERRUPTIBLE);
- timeout = schedule_timeout(2000);
- finish_wait(&kppsd_wait, &wait);
-
- if (timeout)
- shrink_private_vma(&wakeup_sc);
- else
- shrink_private_vma(&default_sc);
+ accelerate_kppsd >>= 1;
+ wait_event_timeout(kppsd_wait, accelerate_kppsd != 0,
+ msecs_to_jiffies(2000));
+ default_sc.may_writepage = !laptop_mode;
+ if (accelerate_kppsd)
+ default_sc.may_writepage = 1;
+ shrink_private_vma(&default_sc);
}
return 0;
}
-
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