[PATCH] mm/compaction: introduce a helper compact_zone_counters_init()

[PATCH] mm/compaction: introduce a helper compact_zone_counters_init()

[Yafang Shao]

This is the follow-up of the
commit "mm/compaction.c: clear total_{migrate,free}_scanned before scanning a new zone".

These counters are used to track activities during compacting a zone,
and they will be set to zero before compacting a new zone in all compact
paths. Move all these common settings into compact_zone() for better
management. A new helper compact_zone_counters_init() is introduced for
this purpose.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Yafang Shao <shaoyafang@didiglobal.com>
---
 mm/compaction.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index a109b45..356348b 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2065,6 +2065,19 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
 	return false;
 }
 
+
+/*
+ * Bellow counters are used to track activities during compacting a zone.
+ * Before compacting a new zone, we should init these counters first.
+ */
+static void compact_zone_counters_init(struct compact_control *cc)
+{
+	cc->total_migrate_scanned = 0;
+	cc->total_free_scanned = 0;
+	cc->nr_migratepages = 0;
+	cc->nr_freepages = 0;
+}
+
 static enum compact_result
 compact_zone(struct compact_control *cc, struct capture_control *capc)
 {
@@ -2075,6 +2088,7 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
 	const bool sync = cc->mode != MIGRATE_ASYNC;
 	bool update_cached;
 
+	compact_zone_counters_init(cc);
 	cc->migratetype = gfpflags_to_migratetype(cc->gfp_mask);
 	ret = compaction_suitable(cc->zone, cc->order, cc->alloc_flags,
 							cc->classzone_idx);
@@ -2278,10 +2292,6 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
 {
 	enum compact_result ret;
 	struct compact_control cc = {
-		.nr_freepages = 0,
-		.nr_migratepages = 0,
-		.total_migrate_scanned = 0,
-		.total_free_scanned = 0,
 		.order = order,
 		.search_order = order,
 		.gfp_mask = gfp_mask,
@@ -2418,10 +2428,6 @@ static void compact_node(int nid)
 		if (!populated_zone(zone))
 			continue;
 
-		cc.nr_freepages = 0;
-		cc.nr_migratepages = 0;
-		cc.total_migrate_scanned = 0;
-		cc.total_free_scanned = 0;
 		cc.zone = zone;
 		INIT_LIST_HEAD(&cc.freepages);
 		INIT_LIST_HEAD(&cc.migratepages);
@@ -2526,8 +2532,6 @@ static void kcompactd_do_work(pg_data_t *pgdat)
 	struct compact_control cc = {
 		.order = pgdat->kcompactd_max_order,
 		.search_order = pgdat->kcompactd_max_order,
-		.total_migrate_scanned = 0,
-		.total_free_scanned = 0,
 		.classzone_idx = pgdat->kcompactd_classzone_idx,
 		.mode = MIGRATE_SYNC_LIGHT,
 		.ignore_skip_hint = false,
@@ -2551,10 +2555,6 @@ static void kcompactd_do_work(pg_data_t *pgdat)
 							COMPACT_CONTINUE)
 			continue;
 
-		cc.nr_freepages = 0;
-		cc.nr_migratepages = 0;
-		cc.total_migrate_scanned = 0;
-		cc.total_free_scanned = 0;
 		cc.zone = zone;
 		INIT_LIST_HEAD(&cc.freepages);
 		INIT_LIST_HEAD(&cc.migratepages);
-- 
1.8.3.1

Re: [PATCH] mm/compaction: introduce a helper compact_zone_counters_init()

[Michal Hocko]

On Tue 23-07-19 04:08:15, Yafang Shao wrote:
> This is the follow-up of the
> commit "mm/compaction.c: clear total_{migrate,free}_scanned before scanning a new zone".
> 
> These counters are used to track activities during compacting a zone,
> and they will be set to zero before compacting a new zone in all compact
> paths. Move all these common settings into compact_zone() for better
> management. A new helper compact_zone_counters_init() is introduced for
> this purpose.

The helper seems excessive a bit because we have a single call site but
other than that this is an improvement to the current fragile and
duplicated code.

I would just get rid of the helper and squash it to your previous patch
which Andrew already took to the mm tree.

> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Cc: Yafang Shao <shaoyafang@didiglobal.com>
> ---
>  mm/compaction.c | 28 ++++++++++++++--------------
>  1 file changed, 14 insertions(+), 14 deletions(-)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index a109b45..356348b 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -2065,6 +2065,19 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
>  	return false;
>  }
>  
> +
> +/*
> + * Bellow counters are used to track activities during compacting a zone.
> + * Before compacting a new zone, we should init these counters first.
> + */
> +static void compact_zone_counters_init(struct compact_control *cc)
> +{
> +	cc->total_migrate_scanned = 0;
> +	cc->total_free_scanned = 0;
> +	cc->nr_migratepages = 0;
> +	cc->nr_freepages = 0;
> +}
> +
>  static enum compact_result
>  compact_zone(struct compact_control *cc, struct capture_control *capc)
>  {
> @@ -2075,6 +2088,7 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
>  	const bool sync = cc->mode != MIGRATE_ASYNC;
>  	bool update_cached;
>  
> +	compact_zone_counters_init(cc);
>  	cc->migratetype = gfpflags_to_migratetype(cc->gfp_mask);
>  	ret = compaction_suitable(cc->zone, cc->order, cc->alloc_flags,
>  							cc->classzone_idx);
> @@ -2278,10 +2292,6 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
>  {
>  	enum compact_result ret;
>  	struct compact_control cc = {
> -		.nr_freepages = 0,
> -		.nr_migratepages = 0,
> -		.total_migrate_scanned = 0,
> -		.total_free_scanned = 0,
>  		.order = order,
>  		.search_order = order,
>  		.gfp_mask = gfp_mask,
> @@ -2418,10 +2428,6 @@ static void compact_node(int nid)
>  		if (!populated_zone(zone))
>  			continue;
>  
> -		cc.nr_freepages = 0;
> -		cc.nr_migratepages = 0;
> -		cc.total_migrate_scanned = 0;
> -		cc.total_free_scanned = 0;
>  		cc.zone = zone;
>  		INIT_LIST_HEAD(&cc.freepages);
>  		INIT_LIST_HEAD(&cc.migratepages);
> @@ -2526,8 +2532,6 @@ static void kcompactd_do_work(pg_data_t *pgdat)
>  	struct compact_control cc = {
>  		.order = pgdat->kcompactd_max_order,
>  		.search_order = pgdat->kcompactd_max_order,
> -		.total_migrate_scanned = 0,
> -		.total_free_scanned = 0,
>  		.classzone_idx = pgdat->kcompactd_classzone_idx,
>  		.mode = MIGRATE_SYNC_LIGHT,
>  		.ignore_skip_hint = false,
> @@ -2551,10 +2555,6 @@ static void kcompactd_do_work(pg_data_t *pgdat)
>  							COMPACT_CONTINUE)
>  			continue;
>  
> -		cc.nr_freepages = 0;
> -		cc.nr_migratepages = 0;
> -		cc.total_migrate_scanned = 0;
> -		cc.total_free_scanned = 0;
>  		cc.zone = zone;
>  		INIT_LIST_HEAD(&cc.freepages);
>  		INIT_LIST_HEAD(&cc.migratepages);
> -- 
> 1.8.3.1

-- 
Michal Hocko
SUSE Labs

Re: [PATCH] mm/compaction: introduce a helper compact_zone_counters_init()

[Yafang Shao]

On Tue, Jul 23, 2019 at 4:12 PM Michal Hocko <mhocko@suse.com> wrote:
>
> On Tue 23-07-19 04:08:15, Yafang Shao wrote:
> > This is the follow-up of the
> > commit "mm/compaction.c: clear total_{migrate,free}_scanned before scanning a new zone".
> >
> > These counters are used to track activities during compacting a zone,
> > and they will be set to zero before compacting a new zone in all compact
> > paths. Move all these common settings into compact_zone() for better
> > management. A new helper compact_zone_counters_init() is introduced for
> > this purpose.
>
> The helper seems excessive a bit because we have a single call site but
> other than that this is an improvement to the current fragile and
> duplicated code.
>

Understood.

> I would just get rid of the helper and squash it to your previous patch
> which Andrew already took to the mm tree.
>

I appreciate it.

Thanks
Yafang

> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> > Cc: Michal Hocko <mhocko@suse.com>
> > Cc: Mel Gorman <mgorman@techsingularity.net>
> > Cc: Yafang Shao <shaoyafang@didiglobal.com>
> > ---
> >  mm/compaction.c | 28 ++++++++++++++--------------
> >  1 file changed, 14 insertions(+), 14 deletions(-)
> >
> > diff --git a/mm/compaction.c b/mm/compaction.c
> > index a109b45..356348b 100644
> > --- a/mm/compaction.c
> > +++ b/mm/compaction.c
> > @@ -2065,6 +2065,19 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
> >       return false;
> >  }
> >
> > +
> > +/*
> > + * Bellow counters are used to track activities during compacting a zone.
> > + * Before compacting a new zone, we should init these counters first.
> > + */
> > +static void compact_zone_counters_init(struct compact_control *cc)
> > +{
> > +     cc->total_migrate_scanned = 0;
> > +     cc->total_free_scanned = 0;
> > +     cc->nr_migratepages = 0;
> > +     cc->nr_freepages = 0;
> > +}
> > +
> >  static enum compact_result
> >  compact_zone(struct compact_control *cc, struct capture_control *capc)
> >  {
> > @@ -2075,6 +2088,7 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
> >       const bool sync = cc->mode != MIGRATE_ASYNC;
> >       bool update_cached;
> >
> > +     compact_zone_counters_init(cc);
> >       cc->migratetype = gfpflags_to_migratetype(cc->gfp_mask);
> >       ret = compaction_suitable(cc->zone, cc->order, cc->alloc_flags,
> >                                                       cc->classzone_idx);
> > @@ -2278,10 +2292,6 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
> >  {
> >       enum compact_result ret;
> >       struct compact_control cc = {
> > -             .nr_freepages = 0,
> > -             .nr_migratepages = 0,
> > -             .total_migrate_scanned = 0,
> > -             .total_free_scanned = 0,
> >               .order = order,
> >               .search_order = order,
> >               .gfp_mask = gfp_mask,
> > @@ -2418,10 +2428,6 @@ static void compact_node(int nid)
> >               if (!populated_zone(zone))
> >                       continue;
> >
> > -             cc.nr_freepages = 0;
> > -             cc.nr_migratepages = 0;
> > -             cc.total_migrate_scanned = 0;
> > -             cc.total_free_scanned = 0;
> >               cc.zone = zone;
> >               INIT_LIST_HEAD(&cc.freepages);
> >               INIT_LIST_HEAD(&cc.migratepages);
> > @@ -2526,8 +2532,6 @@ static void kcompactd_do_work(pg_data_t *pgdat)
> >       struct compact_control cc = {
> >               .order = pgdat->kcompactd_max_order,
> >               .search_order = pgdat->kcompactd_max_order,
> > -             .total_migrate_scanned = 0,
> > -             .total_free_scanned = 0,
> >               .classzone_idx = pgdat->kcompactd_classzone_idx,
> >               .mode = MIGRATE_SYNC_LIGHT,
> >               .ignore_skip_hint = false,
> > @@ -2551,10 +2555,6 @@ static void kcompactd_do_work(pg_data_t *pgdat)
> >                                                       COMPACT_CONTINUE)
> >                       continue;
> >
> > -             cc.nr_freepages = 0;
> > -             cc.nr_migratepages = 0;
> > -             cc.total_migrate_scanned = 0;
> > -             cc.total_free_scanned = 0;
> >               cc.zone = zone;
> >               INIT_LIST_HEAD(&cc.freepages);
> >               INIT_LIST_HEAD(&cc.migratepages);
> > --
> > 1.8.3.1
>
> --
> Michal Hocko
> SUSE Labs

Re: [PATCH] mm/compaction: introduce a helper compact_zone_counters_init()

[Andrew Morton]

On Tue, 23 Jul 2019 10:12:18 +0200 Michal Hocko <mhocko@suse.com> wrote:

> On Tue 23-07-19 04:08:15, Yafang Shao wrote:
> > This is the follow-up of the
> > commit "mm/compaction.c: clear total_{migrate,free}_scanned before scanning a new zone".
> > 
> > These counters are used to track activities during compacting a zone,
> > and they will be set to zero before compacting a new zone in all compact
> > paths. Move all these common settings into compact_zone() for better
> > management. A new helper compact_zone_counters_init() is introduced for
> > this purpose.
> 
> The helper seems excessive a bit because we have a single call site but
> other than that this is an improvement to the current fragile and
> duplicated code.
> 
> I would just get rid of the helper and squash it to your previous patch
> which Andrew already took to the mm tree.

--- a/mm/compaction.c~mm-compaction-clear-total_migratefree_scanned-before-scanning-a-new-zone-fix-fix
+++ a/mm/compaction.c
@@ -2068,19 +2068,6 @@ bool compaction_zonelist_suitable(struct
 	return false;
 }
 
-
-/*
- * Bellow counters are used to track activities during compacting a zone.
- * Before compacting a new zone, we should init these counters first.
- */
-static void compact_zone_counters_init(struct compact_control *cc)
-{
-	cc->total_migrate_scanned = 0;
-	cc->total_free_scanned = 0;
-	cc->nr_migratepages = 0;
-	cc->nr_freepages = 0;
-}
-
 static enum compact_result
 compact_zone(struct compact_control *cc, struct capture_control *capc)
 {
@@ -2091,7 +2078,15 @@ compact_zone(struct compact_control *cc,
 	const bool sync = cc->mode != MIGRATE_ASYNC;
 	bool update_cached;
 
-	compact_zone_counters_init(cc);
+	/*
+	 * These counters track activities during zone compaction.  Initialize
+	 * them before compacting a new zone.
+	 */
+	cc->total_migrate_scanned = 0;
+	cc->total_free_scanned = 0;
+	cc->nr_migratepages = 0;
+	cc->nr_freepages = 0;
+
 	cc->migratetype = gfpflags_to_migratetype(cc->gfp_mask);
 	ret = compaction_suitable(cc->zone, cc->order, cc->alloc_flags,
 							cc->classzone_idx);
_

Re: [PATCH] mm/compaction: introduce a helper compact_zone_counters_init()

[Vlastimil Babka]

On 7/23/19 11:40 PM, Andrew Morton wrote:
> On Tue, 23 Jul 2019 10:12:18 +0200 Michal Hocko <mhocko@suse.com> wrote:
> 
>> On Tue 23-07-19 04:08:15, Yafang Shao wrote:
>>> This is the follow-up of the
>>> commit "mm/compaction.c: clear total_{migrate,free}_scanned before scanning a new zone".
>>>
>>> These counters are used to track activities during compacting a zone,
>>> and they will be set to zero before compacting a new zone in all compact
>>> paths. Move all these common settings into compact_zone() for better
>>> management. A new helper compact_zone_counters_init() is introduced for
>>> this purpose.
>>
>> The helper seems excessive a bit because we have a single call site but
>> other than that this is an improvement to the current fragile and
>> duplicated code.
>>
>> I would just get rid of the helper and squash it to your previous patch
>> which Andrew already took to the mm tree.

I have squashed everything locally, and for the result:

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

Also, why not squash some more?

----8<----
diff --git a/mm/compaction.c b/mm/compaction.c
index dcbe95fa8e28..cfe1457352f9 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2083,6 +2083,8 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
 	cc->total_free_scanned = 0;
 	cc->nr_migratepages = 0;
 	cc->nr_freepages = 0;
+	INIT_LIST_HEAD(&cc->freepages);
+	INIT_LIST_HEAD(&cc->migratepages);
 
 	cc->migratetype = gfpflags_to_migratetype(cc->gfp_mask);
 	ret = compaction_suitable(cc->zone, cc->order, cc->alloc_flags,
@@ -2307,8 +2309,6 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
 
 	if (capture)
 		current->capture_control = &capc;
-	INIT_LIST_HEAD(&cc.freepages);
-	INIT_LIST_HEAD(&cc.migratepages);
 
 	ret = compact_zone(&cc, &capc);
 
@@ -2424,8 +2424,6 @@ static void compact_node(int nid)
 			continue;
 
 		cc.zone = zone;
-		INIT_LIST_HEAD(&cc.freepages);
-		INIT_LIST_HEAD(&cc.migratepages);
 
 		compact_zone(&cc, NULL);
 
@@ -2551,8 +2549,6 @@ static void kcompactd_do_work(pg_data_t *pgdat)
 			continue;
 
 		cc.zone = zone;
-		INIT_LIST_HEAD(&cc.freepages);
-		INIT_LIST_HEAD(&cc.migratepages);
 
 		if (kthread_should_stop())
 			return;

Re: [PATCH] mm/compaction: introduce a helper compact_zone_counters_init()

[Andrew Morton]

On Wed, 24 Jul 2019 15:35:12 +0200 Vlastimil Babka <vbabka@suse.cz> wrote:

> On 7/23/19 11:40 PM, Andrew Morton wrote:
> > On Tue, 23 Jul 2019 10:12:18 +0200 Michal Hocko <mhocko@suse.com> wrote:
> > 
> >> On Tue 23-07-19 04:08:15, Yafang Shao wrote:
> >>> This is the follow-up of the
> >>> commit "mm/compaction.c: clear total_{migrate,free}_scanned before scanning a new zone".
> >>>
> >>> These counters are used to track activities during compacting a zone,
> >>> and they will be set to zero before compacting a new zone in all compact
> >>> paths. Move all these common settings into compact_zone() for better
> >>> management. A new helper compact_zone_counters_init() is introduced for
> >>> this purpose.
> >>
> >> The helper seems excessive a bit because we have a single call site but
> >> other than that this is an improvement to the current fragile and
> >> duplicated code.
> >>
> >> I would just get rid of the helper and squash it to your previous patch
> >> which Andrew already took to the mm tree.
> 
> I have squashed everything locally, and for the result:
> 
> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
> 
> Also, why not squash some more?

An SOB would be nice..

And this?

--- a/mm/compaction.c~mm-compaction-clear-total_migratefree_scanned-before-scanning-a-new-zone-fix-2-fix
+++ a/mm/compaction.c
@@ -2551,10 +2551,10 @@ static void kcompactd_do_work(pg_data_t
 							COMPACT_CONTINUE)
 			continue;
 
-		cc.zone = zone;
-
 		if (kthread_should_stop())
 			return;
+
+		cc.zone = zone;
 		status = compact_zone(&cc, NULL);
 
 		if (status == COMPACT_SUCCESS) {
_

Re: [PATCH] mm/compaction: introduce a helper compact_zone_counters_init()

[Andrew Morton]

On Wed, 24 Jul 2019 17:19:45 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:

> And this?

Here's the current rolled-up state of this patch.

 mm/compaction.c |   35 +++++++++++++----------------------
 1 file changed, 13 insertions(+), 22 deletions(-)

--- a/mm/compaction.c~mm-compaction-clear-total_migratefree_scanned-before-scanning-a-new-zone
+++ a/mm/compaction.c
@@ -2078,6 +2078,17 @@ compact_zone(struct compact_control *cc,
 	const bool sync = cc->mode != MIGRATE_ASYNC;
 	bool update_cached;
 
+	/*
+	 * These counters track activities during zone compaction.  Initialize
+	 * them before compacting a new zone.
+	 */
+	cc->total_migrate_scanned = 0;
+	cc->total_free_scanned = 0;
+	cc->nr_migratepages = 0;
+	cc->nr_freepages = 0;
+	INIT_LIST_HEAD(&cc->freepages);
+	INIT_LIST_HEAD(&cc->migratepages);
+
 	cc->migratetype = gfpflags_to_migratetype(cc->gfp_mask);
 	ret = compaction_suitable(cc->zone, cc->order, cc->alloc_flags,
 							cc->classzone_idx);
@@ -2281,10 +2292,6 @@ static enum compact_result compact_zone_
 {
 	enum compact_result ret;
 	struct compact_control cc = {
-		.nr_freepages = 0,
-		.nr_migratepages = 0,
-		.total_migrate_scanned = 0,
-		.total_free_scanned = 0,
 		.order = order,
 		.search_order = order,
 		.gfp_mask = gfp_mask,
@@ -2305,8 +2312,6 @@ static enum compact_result compact_zone_
 
 	if (capture)
 		current->capture_control = &capc;
-	INIT_LIST_HEAD(&cc.freepages);
-	INIT_LIST_HEAD(&cc.migratepages);
 
 	ret = compact_zone(&cc, &capc);
 
@@ -2408,8 +2413,6 @@ static void compact_node(int nid)
 	struct zone *zone;
 	struct compact_control cc = {
 		.order = -1,
-		.total_migrate_scanned = 0,
-		.total_free_scanned = 0,
 		.mode = MIGRATE_SYNC,
 		.ignore_skip_hint = true,
 		.whole_zone = true,
@@ -2423,11 +2426,7 @@ static void compact_node(int nid)
 		if (!populated_zone(zone))
 			continue;
 
-		cc.nr_freepages = 0;
-		cc.nr_migratepages = 0;
 		cc.zone = zone;
-		INIT_LIST_HEAD(&cc.freepages);
-		INIT_LIST_HEAD(&cc.migratepages);
 
 		compact_zone(&cc, NULL);
 
@@ -2529,8 +2528,6 @@ static void kcompactd_do_work(pg_data_t
 	struct compact_control cc = {
 		.order = pgdat->kcompactd_max_order,
 		.search_order = pgdat->kcompactd_max_order,
-		.total_migrate_scanned = 0,
-		.total_free_scanned = 0,
 		.classzone_idx = pgdat->kcompactd_classzone_idx,
 		.mode = MIGRATE_SYNC_LIGHT,
 		.ignore_skip_hint = false,
@@ -2554,16 +2551,10 @@ static void kcompactd_do_work(pg_data_t
 							COMPACT_CONTINUE)
 			continue;
 
-		cc.nr_freepages = 0;
-		cc.nr_migratepages = 0;
-		cc.total_migrate_scanned = 0;
-		cc.total_free_scanned = 0;
-		cc.zone = zone;
-		INIT_LIST_HEAD(&cc.freepages);
-		INIT_LIST_HEAD(&cc.migratepages);
-
 		if (kthread_should_stop())
 			return;
+
+		cc.zone = zone;
 		status = compact_zone(&cc, NULL);
 
 		if (status == COMPACT_SUCCESS) {
_

Re: [PATCH] mm/compaction: introduce a helper compact_zone_counters_init()

[Vlastimil Babka]

On 7/25/19 2:25 AM, Andrew Morton wrote:
> On Wed, 24 Jul 2019 17:19:45 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:
> 
>> And this?

Makes sense.

> Here's the current rolled-up state of this patch.

Looks good, thanks.