Re: [patch v3 4/6] mm, compaction: embed migration mode in compact_control

Vlastimil Babka
2014-05-07T09:55:29Z

On 05/07/2014 04:22 AM, David Rientjes wrote:
> We're going to want to manipulate the migration mode for compaction in the page
> allocator, and currently compact_control's sync field is only a bool.
>
> Currently, we only do MIGRATE_ASYNC or MIGRATE_SYNC_LIGHT compaction depending
> on the value of this bool. Convert the bool to enum migrate_mode and pass the
> migration mode in directly. Later, we'll want to avoid MIGRATE_SYNC_LIGHT for
> thp allocations in the pagefault patch to avoid unnecessary latency.
>
> This also alters compaction triggered from sysfs, either for the entire system
> or for a node, to force MIGRATE_SYNC.
>
> Suggested-by: Mel Gorman <mgorman@suse.de>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
> include/linux/compaction.h | 4 ++--
> mm/compaction.c | 36 +++++++++++++++++++-----------------
> mm/internal.h | 2 +-
> mm/page_alloc.c | 37 ++++++++++++++++---------------------
> 4 files changed, 38 insertions(+), 41 deletions(-)
>
> diff --git a/include/linux/compaction.h b/include/linux/compaction.h
> --- a/include/linux/compaction.h
> +++ b/include/linux/compaction.h
> @@ -22,7 +22,7 @@ extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
> extern int fragmentation_index(struct zone *zone, unsigned int order);
> extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
> int order, gfp_t gfp_mask, nodemask_t *mask,
> - bool sync, bool *contended);
> + enum migrate_mode sync, bool *contended);

Everywhere else it's 'mode' and only in this function it's still called
'sync', that's confusing.
Afterwards:

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> extern void compact_pgdat(pg_data_t *pgdat, int order);
> extern void reset_isolation_suitable(pg_data_t *pgdat);
> extern unsigned long compaction_suitable(struct zone *zone, int order);
> @@ -91,7 +91,7 @@ static inline bool compaction_restarting(struct zone *zone, int order)
> #else
> static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
> int order, gfp_t gfp_mask, nodemask_t *nodemask,
> - bool sync, bool *contended)
> + enum migrate_mode sync, bool *contended)
> {
> return COMPACT_CONTINUE;
> }
> diff --git a/mm/compaction.c b/mm/compaction.c
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -161,7 +161,8 @@ static void update_pageblock_skip(struct compact_control *cc,
> return;
> if (pfn > zone->compact_cached_migrate_pfn[0])
> zone->compact_cached_migrate_pfn[0] = pfn;
> - if (cc->sync && pfn > zone->compact_cached_migrate_pfn[1])
> + if (cc->mode != MIGRATE_ASYNC &&
> + pfn > zone->compact_cached_migrate_pfn[1])
> zone->compact_cached_migrate_pfn[1] = pfn;
> } else {
> if (cc->finished_update_free)
> @@ -208,7 +209,7 @@ static bool compact_checklock_irqsave(spinlock_t *lock, unsigned long *flags,
> }
>
> /* async aborts if taking too long or contended */
> - if (!cc->sync) {
> + if (cc->mode == MIGRATE_ASYNC) {
> cc->contended = true;
> return false;
> }
> @@ -479,7 +480,8 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
> bool locked = false;
> struct page *page = NULL, *valid_page = NULL;
> bool set_unsuitable = true;
> - const isolate_mode_t mode = (!cc->sync ? ISOLATE_ASYNC_MIGRATE : 0) |
> + const isolate_mode_t mode = (cc->mode == MIGRATE_ASYNC ?
> + ISOLATE_ASYNC_MIGRATE : 0) |
> (unevictable ? ISOLATE_UNEVICTABLE : 0);
>
> /*
> @@ -489,7 +491,7 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
> */
> while (unlikely(too_many_isolated(zone))) {
> /* async migration should just abort */
> - if (!cc->sync)
> + if (cc->mode == MIGRATE_ASYNC)
> return 0;
>
> congestion_wait(BLK_RW_ASYNC, HZ/10);
> @@ -554,7 +556,8 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
> * the minimum amount of work satisfies the allocation
> */
> mt = get_pageblock_migratetype(page);
> - if (!cc->sync && !migrate_async_suitable(mt)) {
> + if (cc->mode == MIGRATE_ASYNC &&
> + !migrate_async_suitable(mt)) {
> set_unsuitable = false;
> goto next_pageblock;
> }
> @@ -990,6 +993,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
> int ret;
> unsigned long start_pfn = zone->zone_start_pfn;
> unsigned long end_pfn = zone_end_pfn(zone);
> + const bool sync = cc->mode != MIGRATE_ASYNC;
>
> ret = compaction_suitable(zone, cc->order);
> switch (ret) {
> @@ -1015,7 +1019,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
> * information on where the scanners should start but check that it
> * is initialised by ensuring the values are within zone boundaries.
> */
> - cc->migrate_pfn = zone->compact_cached_migrate_pfn[cc->sync];
> + cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync];
> cc->free_pfn = zone->compact_cached_free_pfn;
> if (cc->free_pfn < start_pfn || cc->free_pfn > end_pfn) {
> cc->free_pfn = end_pfn & ~(pageblock_nr_pages-1);
> @@ -1049,8 +1053,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
>
> nr_migrate = cc->nr_migratepages;
> err = migrate_pages(&cc->migratepages, compaction_alloc,
> - compaction_free, (unsigned long)cc,
> - cc->sync ? MIGRATE_SYNC_LIGHT : MIGRATE_ASYNC,
> + compaction_free, (unsigned long)cc, cc->mode,
> MR_COMPACTION);
> update_nr_listpages(cc);
> nr_remaining = cc->nr_migratepages;
> @@ -1083,9 +1086,8 @@ out:
> return ret;
> }
>
> -static unsigned long compact_zone_order(struct zone *zone,
> - int order, gfp_t gfp_mask,
> - bool sync, bool *contended)
> +static unsigned long compact_zone_order(struct zone *zone, int order,
> + gfp_t gfp_mask, enum migrate_mode mode, bool *contended)
> {
> unsigned long ret;
> struct compact_control cc = {
> @@ -1094,7 +1096,7 @@ static unsigned long compact_zone_order(struct zone *zone,
> .order = order,
> .migratetype = allocflags_to_migratetype(gfp_mask),
> .zone = zone,
> - .sync = sync,
> + .mode = mode,
> };
> INIT_LIST_HEAD(&cc.freepages);
> INIT_LIST_HEAD(&cc.migratepages);
> @@ -1116,7 +1118,7 @@ int sysctl_extfrag_threshold = 500;
> * @order: The order of the current allocation
> * @gfp_mask: The GFP mask of the current allocation
> * @nodemask: The allowed nodes to allocate from
> - * @sync: Whether migration is synchronous or not
> + * @sync: The migration mode for async, sync light, or sync migration
> * @contended: Return value that is true if compaction was aborted due to lock contention
> * @page: Optionally capture a free page of the requested order during compaction
> *
> @@ -1124,7 +1126,7 @@ int sysctl_extfrag_threshold = 500;
> */
> unsigned long try_to_compact_pages(struct zonelist *zonelist,
> int order, gfp_t gfp_mask, nodemask_t *nodemask,
> - bool sync, bool *contended)
> + enum migrate_mode sync, bool *contended)
> {
> enum zone_type high_zoneidx = gfp_zone(gfp_mask);
> int may_enter_fs = gfp_mask & __GFP_FS;
> @@ -1189,7 +1191,7 @@ static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
> low_wmark_pages(zone), 0, 0))
> compaction_defer_reset(zone, cc->order, false);
> /* Currently async compaction is never deferred. */
> - else if (cc->sync)
> + else if (cc->mode != MIGRATE_ASYNC)
> defer_compaction(zone, cc->order);
> }
>
> @@ -1202,7 +1204,7 @@ void compact_pgdat(pg_data_t *pgdat, int order)
> {
> struct compact_control cc = {
> .order = order,
> - .sync = false,
> + .mode = MIGRATE_ASYNC,
> };
>
> if (!order)
> @@ -1215,7 +1217,7 @@ static void compact_node(int nid)
> {
> struct compact_control cc = {
> .order = -1,
> - .sync = true,
> + .mode = MIGRATE_SYNC,
> .ignore_skip_hint = true,
> };
>
> diff --git a/mm/internal.h b/mm/internal.h
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -134,7 +134,7 @@ struct compact_control {
> unsigned long nr_migratepages; /* Number of pages to migrate */
> unsigned long free_pfn; /* isolate_freepages search base */
> unsigned long migrate_pfn; /* isolate_migratepages search base */
> - bool sync; /* Synchronous migration */
> + enum migrate_mode mode; /* Async or sync migration mode */
> bool ignore_skip_hint; /* Scan blocks even if marked skip */
> bool finished_update_free; /* True when the zone cached pfns are
> * no longer being updated
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2226,7 +2226,7 @@ static struct page *
> __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> struct zonelist *zonelist, enum zone_type high_zoneidx,
> nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
> - int migratetype, bool sync_migration,
> + int migratetype, enum migrate_mode mode,
> bool *contended_compaction, bool *deferred_compaction,
> unsigned long *did_some_progress)
> {
> @@ -2240,7 +2240,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
>
> current->flags |= PF_MEMALLOC;
> *did_some_progress = try_to_compact_pages(zonelist, order, gfp_mask,
> - nodemask, sync_migration,
> + nodemask, mode,
> contended_compaction);
> current->flags &= ~PF_MEMALLOC;
>
> @@ -2273,7 +2273,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> * As async compaction considers a subset of pageblocks, only
> * defer if the failure was a sync compaction failure.
> */
> - if (sync_migration)
> + if (mode != MIGRATE_ASYNC)
> defer_compaction(preferred_zone, order);
>
> cond_resched();
> @@ -2286,9 +2286,8 @@ static inline struct page *
> __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> struct zonelist *zonelist, enum zone_type high_zoneidx,
> nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
> - int migratetype, bool sync_migration,
> - bool *contended_compaction, bool *deferred_compaction,
> - unsigned long *did_some_progress)
> + int migratetype, enum migrate_mode mode, bool *contended_compaction,
> + bool *deferred_compaction, unsigned long *did_some_progress)
> {
> return NULL;
> }
> @@ -2483,7 +2482,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> int alloc_flags;
> unsigned long pages_reclaimed = 0;
> unsigned long did_some_progress;
> - bool sync_migration = false;
> + enum migrate_mode migration_mode = MIGRATE_ASYNC;
> bool deferred_compaction = false;
> bool contended_compaction = false;
>
> @@ -2577,17 +2576,15 @@ rebalance:
> * Try direct compaction. The first pass is asynchronous. Subsequent
> * attempts after direct reclaim are synchronous
> */
> - page = __alloc_pages_direct_compact(gfp_mask, order,
> - zonelist, high_zoneidx,
> - nodemask,
> - alloc_flags, preferred_zone,
> - migratetype, sync_migration,
> - &contended_compaction,
> + page = __alloc_pages_direct_compact(gfp_mask, order, zonelist,
> + high_zoneidx, nodemask, alloc_flags,
> + preferred_zone, migratetype,
> + migration_mode, &contended_compaction,
> &deferred_compaction,
> &did_some_progress);
> if (page)
> goto got_pg;
> - sync_migration = true;
> + migration_mode = MIGRATE_SYNC_LIGHT;
>
> /*
> * If compaction is deferred for high-order allocations, it is because
> @@ -2662,12 +2659,10 @@ rebalance:
> * direct reclaim and reclaim/compaction depends on compaction
> * being called after reclaim so call directly if necessary
> */
> - page = __alloc_pages_direct_compact(gfp_mask, order,
> - zonelist, high_zoneidx,
> - nodemask,
> - alloc_flags, preferred_zone,
> - migratetype, sync_migration,
> - &contended_compaction,
> + page = __alloc_pages_direct_compact(gfp_mask, order, zonelist,
> + high_zoneidx, nodemask, alloc_flags,
> + preferred_zone, migratetype,
> + migration_mode, &contended_compaction,
> &deferred_compaction,
> &did_some_progress);
> if (page)
> @@ -6254,7 +6249,7 @@ int alloc_contig_range(unsigned long start, unsigned long end,
> .nr_migratepages = 0,
> .order = -1,
> .zone = page_zone(pfn_to_page(start)),
> - .sync = true,
> + .sync = MIGRATE_SYNC_LIGHT,
> .ignore_skip_hint = true,
> };
> INIT_LIST_HEAD(&cc.migratepages);
>