Re: [PATCH 05/19] mm: page_alloc: Calculate classzone_idx once from the zonelist ref

From: Mel Gorman
Date: Wed May 14 2014 - 16:29:40 EST


On Tue, May 13, 2014 at 03:25:56PM -0700, Andrew Morton wrote:
> On Tue, 13 May 2014 10:45:36 +0100 Mel Gorman <mgorman@xxxxxxx> wrote:
>
> > There is no need to calculate zone_idx(preferred_zone) multiple times
> > or use the pgdat to figure it out.
> >
>
> This one falls afoul of pending mm/next changes in non-trivial ways.

This should apply on top of what you already have. Thanks.

---8<---
mm: page_alloc: Calculate classzone_idx once from the zonelist ref

There is no need to calculate zone_idx(preferred_zone) multiple times
or use the pgdat to figure it out.

Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
---
mm/page_alloc.c | 60 +++++++++++++++++++++++++++++++++------------------------
1 file changed, 35 insertions(+), 25 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7ce44f9..606eecf 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1948,11 +1948,10 @@ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
static struct page *
get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,
struct zonelist *zonelist, int high_zoneidx, int alloc_flags,
- struct zone *preferred_zone, int migratetype)
+ struct zone *preferred_zone, int classzone_idx, int migratetype)
{
struct zoneref *z;
struct page *page = NULL;
- int classzone_idx;
struct zone *zone;
nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */
int zlc_active = 0; /* set if using zonelist_cache */
@@ -1960,7 +1959,6 @@ get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,
bool consider_zone_dirty = (alloc_flags & ALLOC_WMARK_LOW) &&
(gfp_mask & __GFP_WRITE);

- classzone_idx = zone_idx(preferred_zone);
zonelist_scan:
/*
* Scan zonelist, looking for a zone with enough free.
@@ -2218,7 +2216,7 @@ static inline struct page *
__alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, enum zone_type high_zoneidx,
nodemask_t *nodemask, struct zone *preferred_zone,
- int migratetype)
+ int classzone_idx, int migratetype)
{
struct page *page;

@@ -2236,7 +2234,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask,
order, zonelist, high_zoneidx,
ALLOC_WMARK_HIGH|ALLOC_CPUSET,
- preferred_zone, migratetype);
+ preferred_zone, classzone_idx, migratetype);
if (page)
goto out;

@@ -2271,7 +2269,7 @@ 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, enum migrate_mode mode,
+ int classzone_idx, int migratetype, enum migrate_mode mode,
bool *contended_compaction, bool *deferred_compaction,
unsigned long *did_some_progress)
{
@@ -2299,7 +2297,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
page = get_page_from_freelist(gfp_mask, nodemask,
order, zonelist, high_zoneidx,
alloc_flags & ~ALLOC_NO_WATERMARKS,
- preferred_zone, migratetype);
+ preferred_zone, classzone_idx, migratetype);
if (page) {
preferred_zone->compact_blockskip_flush = false;
compaction_defer_reset(preferred_zone, order, true);
@@ -2331,7 +2329,8 @@ 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, enum migrate_mode mode, bool *contended_compaction,
+ int classzone_idx, int migratetype,
+ enum migrate_mode mode, bool *contended_compaction,
bool *deferred_compaction, unsigned long *did_some_progress)
{
return NULL;
@@ -2387,7 +2386,7 @@ static inline struct page *
__alloc_pages_direct_reclaim(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, unsigned long *did_some_progress)
+ int classzone_idx, int migratetype, unsigned long *did_some_progress)
{
struct page *page = NULL;
bool drained = false;
@@ -2405,7 +2404,8 @@ retry:
page = get_page_from_freelist(gfp_mask, nodemask, order,
zonelist, high_zoneidx,
alloc_flags & ~ALLOC_NO_WATERMARKS,
- preferred_zone, migratetype);
+ preferred_zone, classzone_idx,
+ migratetype);

/*
* If an allocation failed after direct reclaim, it could be because
@@ -2430,14 +2430,14 @@ static inline struct page *
__alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, enum zone_type high_zoneidx,
nodemask_t *nodemask, struct zone *preferred_zone,
- int migratetype)
+ int classzone_idx, int migratetype)
{
struct page *page;

do {
page = get_page_from_freelist(gfp_mask, nodemask, order,
zonelist, high_zoneidx, ALLOC_NO_WATERMARKS,
- preferred_zone, migratetype);
+ preferred_zone, classzone_idx, migratetype);

if (!page && gfp_mask & __GFP_NOFAIL)
wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/50);
@@ -2538,7 +2538,7 @@ static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, enum zone_type high_zoneidx,
nodemask_t *nodemask, struct zone *preferred_zone,
- int migratetype)
+ int classzone_idx, int migratetype)
{
const gfp_t wait = gfp_mask & __GFP_WAIT;
struct page *page = NULL;
@@ -2587,15 +2587,19 @@ restart:
* Find the true preferred zone if the allocation is unconstrained by
* cpusets.
*/
- if (!(alloc_flags & ALLOC_CPUSET) && !nodemask)
- first_zones_zonelist(zonelist, high_zoneidx, NULL,
- &preferred_zone);
+ if (!(alloc_flags & ALLOC_CPUSET) && !nodemask) {
+ struct zoneref *preferred_zoneref;
+ preferred_zoneref = first_zones_zonelist(zonelist, high_zoneidx,
+ nodemask ? : &cpuset_current_mems_allowed,
+ &preferred_zone);
+ classzone_idx = zonelist_zone_idx(preferred_zoneref);
+ }

rebalance:
/* This is the last chance, in general, before the goto nopage. */
page = get_page_from_freelist(gfp_mask, nodemask, order, zonelist,
high_zoneidx, alloc_flags & ~ALLOC_NO_WATERMARKS,
- preferred_zone, migratetype);
+ preferred_zone, classzone_idx, migratetype);
if (page)
goto got_pg;

@@ -2610,7 +2614,7 @@ rebalance:

page = __alloc_pages_high_priority(gfp_mask, order,
zonelist, high_zoneidx, nodemask,
- preferred_zone, migratetype);
+ preferred_zone, classzone_idx, migratetype);
if (page) {
goto got_pg;
}
@@ -2641,7 +2645,8 @@ rebalance:
*/
page = __alloc_pages_direct_compact(gfp_mask, order, zonelist,
high_zoneidx, nodemask, alloc_flags,
- preferred_zone, migratetype,
+ preferred_zone,
+ classzone_idx, migratetype,
migration_mode, &contended_compaction,
&deferred_compaction,
&did_some_progress);
@@ -2671,7 +2676,8 @@ rebalance:
zonelist, high_zoneidx,
nodemask,
alloc_flags, preferred_zone,
- migratetype, &did_some_progress);
+ classzone_idx, migratetype,
+ &did_some_progress);
if (page)
goto got_pg;

@@ -2690,7 +2696,7 @@ rebalance:
page = __alloc_pages_may_oom(gfp_mask, order,
zonelist, high_zoneidx,
nodemask, preferred_zone,
- migratetype);
+ classzone_idx, migratetype);
if (page)
goto got_pg;

@@ -2731,7 +2737,8 @@ rebalance:
*/
page = __alloc_pages_direct_compact(gfp_mask, order, zonelist,
high_zoneidx, nodemask, alloc_flags,
- preferred_zone, migratetype,
+ preferred_zone,
+ classzone_idx, migratetype,
migration_mode, &contended_compaction,
&deferred_compaction,
&did_some_progress);
@@ -2760,10 +2767,12 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
{
enum zone_type high_zoneidx = gfp_zone(gfp_mask);
struct zone *preferred_zone;
+ struct zoneref *preferred_zoneref;
struct page *page = NULL;
int migratetype = allocflags_to_migratetype(gfp_mask);
unsigned int cpuset_mems_cookie;
int alloc_flags = ALLOC_WMARK_LOW|ALLOC_CPUSET|ALLOC_FAIR;
+ int classzone_idx;

gfp_mask &= gfp_allowed_mask;

@@ -2786,11 +2795,12 @@ retry_cpuset:
cpuset_mems_cookie = read_mems_allowed_begin();

/* The preferred zone is used for statistics later */
- first_zones_zonelist(zonelist, high_zoneidx,
+ preferred_zoneref = first_zones_zonelist(zonelist, high_zoneidx,
nodemask ? : &cpuset_current_mems_allowed,
&preferred_zone);
if (!preferred_zone)
goto out;
+ classzone_idx = zonelist_zone_idx(preferred_zoneref);

#ifdef CONFIG_CMA
if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
@@ -2800,7 +2810,7 @@ retry:
/* First allocation attempt */
page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
zonelist, high_zoneidx, alloc_flags,
- preferred_zone, migratetype);
+ preferred_zone, classzone_idx, migratetype);
if (unlikely(!page)) {
/*
* The first pass makes sure allocations are spread
@@ -2826,7 +2836,7 @@ retry:
gfp_mask = memalloc_noio_flags(gfp_mask);
page = __alloc_pages_slowpath(gfp_mask, order,
zonelist, high_zoneidx, nodemask,
- preferred_zone, migratetype);
+ preferred_zone, classzone_idx, migratetype);
}

trace_mm_page_alloc(page, order, gfp_mask, migratetype);
--
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