linux-4.4.1/isolate_migratepages_block()
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開始行:
*参照元 [#v3a8a1fb]
#backlinks
*説明 [#a7fbdb14]
-パス: [[linux-4.4.1/mm/compaction.c]]
-FIXME: これは何？
--説明
**引数 [#x9175fa9]
-struct compact_control *cc
--
--[[linux-4.4.1/compact_control]]
-unsigned long low_pfn
--
-unsigned long end_pfn
--
-isolate_mode_t isolate_mode
--
--[[linux-4.4.1/isolate_mode_t]]
**返り値 [#wddf765a]
-unsigned long
--
**参考 [#d55440ec]
*実装 [#p25b927c]
/**
* isolate_migratepages_block() - isolate all migrate-ab...
* a single pageblock
* @cc: Compaction control structure.
* @low_pfn: The first PFN to isolate
* @end_pfn: The one-past-the-last PFN to isolate, withi...
* @isolate_mode: Isolation mode to be used.
*
* Isolate all pages that can be migrated from the range...
* [low_pfn, end_pfn). The range is expected to be withi...
* Returns zero if there is a fatal signal pending, othe...
* first page that was not scanned (which may be both le...
* than end_pfn).
*
* The pages are isolated on cc->migratepages list (not ...
* and cc->nr_migratepages is updated accordingly. The c...
* is neither read nor updated.
*/
static unsigned long
isolate_migratepages_block(struct compact_control *cc, u...
unsigned long end_pfn, isolate_mode_t isolate_mode)
{
struct zone *zone = cc->zone;
unsigned long nr_scanned = 0, nr_isolated = 0;
struct list_head *migratelist = &cc->migratepages;
struct lruvec *lruvec;
unsigned long flags = 0;
bool locked = false;
struct page *page = NULL, *valid_page = NULL;
unsigned long start_pfn = low_pfn;
-
--[[linux-4.4.1/zone]]
--[[linux-4.4.1/list_head]]
--[[linux-4.4.1/lruvec]]
--[[linux-4.4.1/page]]
/*
* Ensure that there are not too many pages isolated fr...
* list by either parallel reclaimers or compaction. If...
* delay for some time until fewer pages are isolated
*/
while (unlikely(too_many_isolated(zone))) {
/* async migration should just abort */
if (cc->mode == MIGRATE_ASYNC)
return 0;
congestion_wait(BLK_RW_ASYNC, HZ/10);
if (fatal_signal_pending(current))
return 0;
}
-
--[[linux-4.4.1/unlikely()]]
--[[linux-4.4.1/too_many_isolated()]]
--[[linux-4.4.1/congestion_wait()]]
--[[linux-4.4.1/fatal_signal_pending()]]
if (compact_should_abort(cc))
return 0;
-
--[[linux-4.4.1/compact_should_abort()]]
/* Time to isolate some pages for migration */
for (; low_pfn < end_pfn; low_pfn++) {
bool is_lru;
/*
* Periodically drop the lock (if held) regardless of ...
* contention, to give chance to IRQs. Abort async com...
* if contended.
*/
if (!(low_pfn % SWAP_CLUSTER_MAX)
&& compact_unlock_should_abort(&zone->lru_lock, fl...
&locked, cc))
break;
-
--[[linux-4.4.1/compact_unlock_should_abort()]]
if (!pfn_valid_within(low_pfn))
continue;
nr_scanned++;
-
--[[linux-4.4.1/pfn_valid_within()]]
page = pfn_to_page(low_pfn);
if (!valid_page)
valid_page = page;
-
--[[linux-4.4.1/pfn_to_page()]]
/*
* Skip if free. We read page order here without zone ...
* which is generally unsafe, but the race window is s...
* the worst thing that can happen is that we skip some
* potential isolation targets.
*/
if (PageBuddy(page)) {
unsigned long freepage_order = page_order_unsafe(page);
/*
* Without lock, we cannot be sure that what we got is
* a valid page order. Consider only values in the
* valid order range to prevent low_pfn overflow.
*/
if (freepage_order > 0 && freepage_order < MAX_ORDER)
low_pfn += (1UL << freepage_order) - 1;
continue;
}
-
--[[linux-4.4.1/PageBuddy()]]
--[[linux-4.4.1/page_order_unsafe()]]
/*
* Check may be lockless but that's ok as we recheck l...
* It's possible to migrate LRU pages and balloon pages
* Skip any other type of page
*/
is_lru = PageLRU(page);
if (!is_lru) {
if (unlikely(balloon_page_movable(page))) {
if (balloon_page_isolate(page)) {
/* Successfully isolated */
goto isolate_success;
}
}
}
-
--[[linux-4.4.1/PageLRU()]]
--[[linux-4.4.1/balloon_page_movable()]]
--[[linux-4.4.1/balloon_page_isolate()]]
/*
* Regardless of being on LRU, compound pages such as ...
* hugetlbfs are not to be compacted. We can potential...
* a lot of iterations if we skip them at once. The ch...
* racy, but we can consider only valid values and the...
* danger is skipping too much.
*/
if (PageCompound(page)) {
unsigned int comp_order = compound_order(page);
if (likely(comp_order < MAX_ORDER))
low_pfn += (1UL << comp_order) - 1;
continue;
}
-
--[[linux-4.4.1/PageCompound()]]
--[[linux-4.4.1/compound_order()]]
if (!is_lru)
continue;
/*
* Migration will fail if an anonymous page is pinned ...
* so avoid taking lru_lock and isolating it unnecessa...
* admittedly racy check.
*/
if (!page_mapping(page) &&
page_count(page) > page_mapcount(page))
continue;
-
--[[linux-4.4.1/page_mapping()]]
--[[linux-4.4.1/page_count()]]
--[[linux-4.4.1/page_mapcount()]]
/* If we already hold the lock, we can skip some reche...
if (!locked) {
locked = compact_trylock_irqsave(&zone->lru_lock,
&flags, cc);
if (!locked)
break;
/* Recheck PageLRU and PageCompound under lock */
if (!PageLRU(page))
continue;
/*
* Page become compound since the non-locked check,
* and it's on LRU. It can only be a THP so the order
* is safe to read and it's 0 for tail pages.
*/
if (unlikely(PageCompound(page))) {
low_pfn += (1UL << compound_order(page)) - 1;
continue;
}
}
-
--[[linux-4.4.1/compact_trylock_irqsave()]]
--[[linux-4.4.1/PageLRU()]]
--[[linux-4.4.1/PageCompound()]]
--[[linux-4.4.1/compound_order()]]
lruvec = mem_cgroup_page_lruvec(page, zone);
-
--[[linux-4.4.1/mem_cgroup_page_lruvec()]]
/* Try isolate the page */
if (__isolate_lru_page(page, isolate_mode) != 0)
continue;
VM_BUG_ON_PAGE(PageCompound(page), page);
-
--[[linux-4.4.1/__isolate_lru_page()]]
--[[linux-4.4.1/VM_BUG_ON_PAGE()]]
--[[linux-4.4.1/PageCompound()]]
/* Successfully isolated */
del_page_from_lru_list(page, lruvec, page_lru(page));
-
--[[linux-4.4.1/del_page_from_lru_list()]]
--[[linux-4.4.1/page_lru()]]
isolate_success:
list_add(&page->lru, migratelist);
cc->nr_migratepages++;
nr_isolated++;
-
--[[linux-4.4.1/list_add()]]
/* Avoid isolating too much */
if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
++low_pfn;
break;
}
}
/*
* The PageBuddy() check could have potentially brought...
* the range to be scanned.
*/
if (unlikely(low_pfn > end_pfn))
low_pfn = end_pfn;
if (locked)
spin_unlock_irqrestore(&zone->lru_lock, flags);
-
--[[linux-4.4.1/spin_unlock_irqrestore()]]
/*
* Update the pageblock-skip information and cached sca...
* if the whole pageblock was scanned without isolating...
*/
if (low_pfn == end_pfn)
update_pageblock_skip(cc, valid_page, nr_isolated, tru...
trace_mm_compaction_isolate_migratepages(start_pfn, low...
nr_scanned, nr_isolated);
count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
if (nr_isolated)
count_compact_events(COMPACTISOLATED, nr_isolated);
-
--[[linux-4.4.1/update_pageblock_skip()]]
--[[linux-4.4.1/trace_mm_compaction_isolate_migratepages(...
--[[linux-4.4.1/count_compact_events()]]
return low_pfn;
}
*コメント [#w5343847]
終了行:
*参照元 [#v3a8a1fb]
#backlinks
*説明 [#a7fbdb14]
-パス: [[linux-4.4.1/mm/compaction.c]]
-FIXME: これは何？
--説明
**引数 [#x9175fa9]
-struct compact_control *cc
--
--[[linux-4.4.1/compact_control]]
-unsigned long low_pfn
--
-unsigned long end_pfn
--
-isolate_mode_t isolate_mode
--
--[[linux-4.4.1/isolate_mode_t]]
**返り値 [#wddf765a]
-unsigned long
--
**参考 [#d55440ec]
*実装 [#p25b927c]
/**
* isolate_migratepages_block() - isolate all migrate-ab...
* a single pageblock
* @cc: Compaction control structure.
* @low_pfn: The first PFN to isolate
* @end_pfn: The one-past-the-last PFN to isolate, withi...
* @isolate_mode: Isolation mode to be used.
*
* Isolate all pages that can be migrated from the range...
* [low_pfn, end_pfn). The range is expected to be withi...
* Returns zero if there is a fatal signal pending, othe...
* first page that was not scanned (which may be both le...
* than end_pfn).
*
* The pages are isolated on cc->migratepages list (not ...
* and cc->nr_migratepages is updated accordingly. The c...
* is neither read nor updated.
*/
static unsigned long
isolate_migratepages_block(struct compact_control *cc, u...
unsigned long end_pfn, isolate_mode_t isolate_mode)
{
struct zone *zone = cc->zone;
unsigned long nr_scanned = 0, nr_isolated = 0;
struct list_head *migratelist = &cc->migratepages;
struct lruvec *lruvec;
unsigned long flags = 0;
bool locked = false;
struct page *page = NULL, *valid_page = NULL;
unsigned long start_pfn = low_pfn;
-
--[[linux-4.4.1/zone]]
--[[linux-4.4.1/list_head]]
--[[linux-4.4.1/lruvec]]
--[[linux-4.4.1/page]]
/*
* Ensure that there are not too many pages isolated fr...
* list by either parallel reclaimers or compaction. If...
* delay for some time until fewer pages are isolated
*/
while (unlikely(too_many_isolated(zone))) {
/* async migration should just abort */
if (cc->mode == MIGRATE_ASYNC)
return 0;
congestion_wait(BLK_RW_ASYNC, HZ/10);
if (fatal_signal_pending(current))
return 0;
}
-
--[[linux-4.4.1/unlikely()]]
--[[linux-4.4.1/too_many_isolated()]]
--[[linux-4.4.1/congestion_wait()]]
--[[linux-4.4.1/fatal_signal_pending()]]
if (compact_should_abort(cc))
return 0;
-
--[[linux-4.4.1/compact_should_abort()]]
/* Time to isolate some pages for migration */
for (; low_pfn < end_pfn; low_pfn++) {
bool is_lru;
/*
* Periodically drop the lock (if held) regardless of ...
* contention, to give chance to IRQs. Abort async com...
* if contended.
*/
if (!(low_pfn % SWAP_CLUSTER_MAX)
&& compact_unlock_should_abort(&zone->lru_lock, fl...
&locked, cc))
break;
-
--[[linux-4.4.1/compact_unlock_should_abort()]]
if (!pfn_valid_within(low_pfn))
continue;
nr_scanned++;
-
--[[linux-4.4.1/pfn_valid_within()]]
page = pfn_to_page(low_pfn);
if (!valid_page)
valid_page = page;
-
--[[linux-4.4.1/pfn_to_page()]]
/*
* Skip if free. We read page order here without zone ...
* which is generally unsafe, but the race window is s...
* the worst thing that can happen is that we skip some
* potential isolation targets.
*/
if (PageBuddy(page)) {
unsigned long freepage_order = page_order_unsafe(page);
/*
* Without lock, we cannot be sure that what we got is
* a valid page order. Consider only values in the
* valid order range to prevent low_pfn overflow.
*/
if (freepage_order > 0 && freepage_order < MAX_ORDER)
low_pfn += (1UL << freepage_order) - 1;
continue;
}
-
--[[linux-4.4.1/PageBuddy()]]
--[[linux-4.4.1/page_order_unsafe()]]
/*
* Check may be lockless but that's ok as we recheck l...
* It's possible to migrate LRU pages and balloon pages
* Skip any other type of page
*/
is_lru = PageLRU(page);
if (!is_lru) {
if (unlikely(balloon_page_movable(page))) {
if (balloon_page_isolate(page)) {
/* Successfully isolated */
goto isolate_success;
}
}
}
-
--[[linux-4.4.1/PageLRU()]]
--[[linux-4.4.1/balloon_page_movable()]]
--[[linux-4.4.1/balloon_page_isolate()]]
/*
* Regardless of being on LRU, compound pages such as ...
* hugetlbfs are not to be compacted. We can potential...
* a lot of iterations if we skip them at once. The ch...
* racy, but we can consider only valid values and the...
* danger is skipping too much.
*/
if (PageCompound(page)) {
unsigned int comp_order = compound_order(page);
if (likely(comp_order < MAX_ORDER))
low_pfn += (1UL << comp_order) - 1;
continue;
}
-
--[[linux-4.4.1/PageCompound()]]
--[[linux-4.4.1/compound_order()]]
if (!is_lru)
continue;
/*
* Migration will fail if an anonymous page is pinned ...
* so avoid taking lru_lock and isolating it unnecessa...
* admittedly racy check.
*/
if (!page_mapping(page) &&
page_count(page) > page_mapcount(page))
continue;
-
--[[linux-4.4.1/page_mapping()]]
--[[linux-4.4.1/page_count()]]
--[[linux-4.4.1/page_mapcount()]]
/* If we already hold the lock, we can skip some reche...
if (!locked) {
locked = compact_trylock_irqsave(&zone->lru_lock,
&flags, cc);
if (!locked)
break;
/* Recheck PageLRU and PageCompound under lock */
if (!PageLRU(page))
continue;
/*
* Page become compound since the non-locked check,
* and it's on LRU. It can only be a THP so the order
* is safe to read and it's 0 for tail pages.
*/
if (unlikely(PageCompound(page))) {
low_pfn += (1UL << compound_order(page)) - 1;
continue;
}
}
-
--[[linux-4.4.1/compact_trylock_irqsave()]]
--[[linux-4.4.1/PageLRU()]]
--[[linux-4.4.1/PageCompound()]]
--[[linux-4.4.1/compound_order()]]
lruvec = mem_cgroup_page_lruvec(page, zone);
-
--[[linux-4.4.1/mem_cgroup_page_lruvec()]]
/* Try isolate the page */
if (__isolate_lru_page(page, isolate_mode) != 0)
continue;
VM_BUG_ON_PAGE(PageCompound(page), page);
-
--[[linux-4.4.1/__isolate_lru_page()]]
--[[linux-4.4.1/VM_BUG_ON_PAGE()]]
--[[linux-4.4.1/PageCompound()]]
/* Successfully isolated */
del_page_from_lru_list(page, lruvec, page_lru(page));
-
--[[linux-4.4.1/del_page_from_lru_list()]]
--[[linux-4.4.1/page_lru()]]
isolate_success:
list_add(&page->lru, migratelist);
cc->nr_migratepages++;
nr_isolated++;
-
--[[linux-4.4.1/list_add()]]
/* Avoid isolating too much */
if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
++low_pfn;
break;
}
}
/*
* The PageBuddy() check could have potentially brought...
* the range to be scanned.
*/
if (unlikely(low_pfn > end_pfn))
low_pfn = end_pfn;
if (locked)
spin_unlock_irqrestore(&zone->lru_lock, flags);
-
--[[linux-4.4.1/spin_unlock_irqrestore()]]
/*
* Update the pageblock-skip information and cached sca...
* if the whole pageblock was scanned without isolating...
*/
if (low_pfn == end_pfn)
update_pageblock_skip(cc, valid_page, nr_isolated, tru...
trace_mm_compaction_isolate_migratepages(start_pfn, low...
nr_scanned, nr_isolated);
count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
if (nr_isolated)
count_compact_events(COMPACTISOLATED, nr_isolated);
-
--[[linux-4.4.1/update_pageblock_skip()]]
--[[linux-4.4.1/trace_mm_compaction_isolate_migratepages(...
--[[linux-4.4.1/count_compact_events()]]
return low_pfn;
}
*コメント [#w5343847]
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