return true;
}
+/*
+ * Aside from avoiding lock contention, compaction also periodically checks
+ * need_resched() and either schedules in sync compaction or aborts async
+ * compaction. This is similar to what compact_checklock_irqsave() does, but
+ * is used where no lock is concerned.
+ *
+ * Returns false when no scheduling was needed, or sync compaction scheduled.
+ * Returns true when async compaction should abort.
+ */
+static inline bool compact_should_abort(struct compact_control *cc)
+{
+ /* async compaction aborts if contended */
+ if (need_resched()) {
+ if (cc->mode == MIGRATE_ASYNC) {
+ cc->contended = true;
+ return true;
+ }
+
+ cond_resched();
+ }
+
+ return false;
+}
+
/* Returns true if the page is within a block suitable for migration to */
static bool suitable_migration_target(struct page *page)
{
return 0;
}
+ if (compact_should_abort(cc))
+ return 0;
+
/* Time to isolate some pages for migration */
- cond_resched();
for (; low_pfn < end_pfn; low_pfn++) {
/* give a chance to irqs before checking need_resched() */
if (locked && !(low_pfn % SWAP_CLUSTER_MAX)) {
unsigned long block_start_pfn; /* start of current pageblock */
unsigned long block_end_pfn; /* end of current pageblock */
unsigned long low_pfn; /* lowest pfn scanner is able to scan */
- unsigned long next_free_pfn; /* start pfn for scaning at next round */
int nr_freepages = cc->nr_freepages;
struct list_head *freelist = &cc->freepages;
low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages);
/*
- * If no pages are isolated, the block_start_pfn < low_pfn check
- * will kick in.
- */
- next_free_pfn = 0;
-
- /*
* Isolate free pages until enough are available to migrate the
* pages on cc->migratepages. We stop searching if the migrate
* and free page scanners meet or enough free pages are isolated.
/*
* This can iterate a massively long zone without finding any
* suitable migration targets, so periodically check if we need
- * to schedule.
+ * to schedule, or even abort async compaction.
*/
- cond_resched();
+ if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
+ && compact_should_abort(cc))
+ break;
if (!pfn_valid(block_start_pfn))
continue;
continue;
/* Found a block suitable for isolating free pages from */
+ cc->free_pfn = block_start_pfn;
isolated = isolate_freepages_block(cc, block_start_pfn,
block_end_pfn, freelist, false);
nr_freepages += isolated;
/*
- * Record the highest PFN we isolated pages from. When next
- * looking for free pages, the search will restart here as
- * page migration may have returned some pages to the allocator
+ * Set a flag that we successfully isolated in this pageblock.
+ * In the next loop iteration, zone->compact_cached_free_pfn
+ * will not be updated and thus it will effectively contain the
+ * highest pageblock we isolated pages from.
*/
- if (isolated && next_free_pfn == 0) {
+ if (isolated)
cc->finished_update_free = true;
- next_free_pfn = block_start_pfn;
- }
+
+ /*
+ * isolate_freepages_block() might have aborted due to async
+ * compaction being contended
+ */
+ if (cc->contended)
+ break;
}
/* split_free_page does not map the pages */
* so that compact_finished() may detect this
*/
if (block_start_pfn < low_pfn)
- next_free_pfn = cc->migrate_pfn;
+ cc->free_pfn = cc->migrate_pfn;
- cc->free_pfn = next_free_pfn;
cc->nr_freepages = nr_freepages;
}
struct compact_control *cc = (struct compact_control *)data;
struct page *freepage;
- /* Isolate free pages if necessary */
+ /*
+ * Isolate free pages if necessary, and if we are not aborting due to
+ * contention.
+ */
if (list_empty(&cc->freepages)) {
- isolate_freepages(cc->zone, cc);
+ if (!cc->contended)
+ isolate_freepages(cc->zone, cc);
if (list_empty(&cc->freepages))
return NULL;
cc->nr_freepages++;
}
-/*
- * We cannot control nr_migratepages fully when migration is running as
- * migrate_pages() has no knowledge of of compact_control. When migration is
- * complete, we count the number of pages on the list by hand.
- */
-static void update_nr_listpages(struct compact_control *cc)
-{
- int nr_migratepages = 0;
- struct page *page;
-
- list_for_each_entry(page, &cc->migratepages, lru)
- nr_migratepages++;
-
- cc->nr_migratepages = nr_migratepages;
-}
-
/* possible outcome of isolate_migratepages */
typedef enum {
ISOLATE_ABORT, /* Abort compaction now */
unsigned int order;
unsigned long watermark;
- if (fatal_signal_pending(current))
+ if (cc->contended || fatal_signal_pending(current))
return COMPACT_PARTIAL;
/* Compaction run completes if the migrate and free scanner meet */
migrate_prep_local();
while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
- unsigned long nr_migrate, nr_remaining;
int err;
switch (isolate_migratepages(zone, cc)) {
;
}
- nr_migrate = cc->nr_migratepages;
+ if (!cc->nr_migratepages)
+ continue;
+
err = migrate_pages(&cc->migratepages, compaction_alloc,
compaction_free, (unsigned long)cc, cc->mode,
MR_COMPACTION);
- update_nr_listpages(cc);
- nr_remaining = cc->nr_migratepages;
- trace_mm_compaction_migratepages(nr_migrate - nr_remaining,
- nr_remaining);
+ trace_mm_compaction_migratepages(cc->nr_migratepages, err,
+ &cc->migratepages);
- /* Release isolated pages not migrated */
+ /* All pages were either migrated or will be released */
+ cc->nr_migratepages = 0;
if (err) {
putback_movable_pages(&cc->migratepages);
- cc->nr_migratepages = 0;
/*
* migrate_pages() may return -ENOMEM when scanners meet
* and we want compact_finished() to detect it
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / blobdiff