Messages in this thread Patch in this message | | | Date | Tue, 18 Aug 2009 13:47:52 +0200 | From | Nick Piggin <> | Subject | Re: [PATCH 3/3] page-allocator: Move pcp static fields for high and batch off-pcp and onto the zone |
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On Tue, Aug 18, 2009 at 12:16:02PM +0100, Mel Gorman wrote: > Having multiple lists per PCPU increased the size of the per-pcpu > structure. Two of the fields, high and batch, do not change within a > zone making that information redundant. This patch moves those fields > off the PCP and onto the zone to reduce the size of the PCPU.
Hmm.. I did have some patches a long long time ago that among other things made the lists larger for the local node only....
But I guess if something like that is ever shown to be a good idea then we can go back to the old scheme. So yeah this seems OK.
> > Signed-off-by: Mel Gorman <mel@csn.ul.ie> > --- > include/linux/mmzone.h | 9 +++++---- > mm/page_alloc.c | 47 +++++++++++++++++++++++++---------------------- > mm/vmstat.c | 4 ++-- > 3 files changed, 32 insertions(+), 28 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 6e0b624..57a3ef0 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -167,12 +167,10 @@ enum zone_watermarks { > #define high_wmark_pages(z) (z->watermark[WMARK_HIGH]) > > struct per_cpu_pages { > - int count; /* number of pages in the list */ > - int high; /* high watermark, emptying needed */ > - int batch; /* chunk size for buddy add/remove */ > - > /* Lists of pages, one per migrate type stored on the pcp-lists */ > struct list_head lists[MIGRATE_PCPTYPES]; > + > + int count; /* number of pages in the list */ > }; > > struct per_cpu_pageset { > @@ -284,6 +282,9 @@ struct zone { > /* zone watermarks, access with *_wmark_pages(zone) macros */ > unsigned long watermark[NR_WMARK]; > > + int pcp_high; /* high watermark, emptying needed */ > + int pcp_batch; /* chunk size for buddy add/remove */ > + > /* > * We don't know if the memory that we're going to allocate will be freeable > * or/and it will be released eventually, so to avoid totally wasting several > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index dd3f306..65cdfbf 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -988,8 +988,8 @@ void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp) > int to_drain; > > local_irq_save(flags); > - if (pcp->count >= pcp->batch) > - to_drain = pcp->batch; > + if (pcp->count >= zone->pcp_batch) > + to_drain = zone->pcp_batch; > else > to_drain = pcp->count; > free_pcppages_bulk(zone, to_drain, pcp); > @@ -1129,9 +1129,9 @@ static void free_hot_cold_page(struct page *page, int cold) > else > list_add(&page->lru, &pcp->lists[migratetype]); > pcp->count++; > - if (pcp->count >= pcp->high) { > - free_pcppages_bulk(zone, pcp->batch, pcp); > - pcp->count -= pcp->batch; > + if (pcp->count >= zone->pcp_high) { > + free_pcppages_bulk(zone, zone->pcp_batch, pcp); > + pcp->count -= zone->pcp_batch; > } > > out: > @@ -1199,7 +1199,7 @@ again: > local_irq_save(flags); > if (list_empty(list)) { > pcp->count += rmqueue_bulk(zone, 0, > - pcp->batch, list, > + zone->pcp_batch, list, > migratetype, cold); > if (unlikely(list_empty(list))) > goto failed; > @@ -2178,8 +2178,8 @@ void show_free_areas(void) > pageset = zone_pcp(zone, cpu); > > printk("CPU %4d: hi:%5d, btch:%4d usd:%4d\n", > - cpu, pageset->pcp.high, > - pageset->pcp.batch, pageset->pcp.count); > + cpu, zone->pcp_high, > + zone->pcp_batch, pageset->pcp.count); > } > } > > @@ -3045,7 +3045,9 @@ static int zone_batchsize(struct zone *zone) > #endif > } > > -static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch) > +static void setup_pageset(struct zone *zone, > + struct per_cpu_pageset *p, > + unsigned long batch) > { > struct per_cpu_pages *pcp; > int migratetype; > @@ -3054,8 +3056,8 @@ static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch) > > pcp = &p->pcp; > pcp->count = 0; > - pcp->high = 6 * batch; > - pcp->batch = max(1UL, 1 * batch); > + zone->pcp_high = 6 * batch; > + zone->pcp_batch = max(1UL, 1 * batch); > for (migratetype = 0; migratetype < MIGRATE_PCPTYPES; migratetype++) > INIT_LIST_HEAD(&pcp->lists[migratetype]); > } > @@ -3065,16 +3067,17 @@ static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch) > * to the value high for the pageset p. > */ > > -static void setup_pagelist_highmark(struct per_cpu_pageset *p, > +static void setup_pagelist_highmark(struct zone *zone, > + struct per_cpu_pageset *p, > unsigned long high) > { > struct per_cpu_pages *pcp; > > pcp = &p->pcp; > - pcp->high = high; > - pcp->batch = max(1UL, high/4); > + zone->pcp_high = high; > + zone->pcp_batch = max(1UL, high/4); > if ((high/4) > (PAGE_SHIFT * 8)) > - pcp->batch = PAGE_SHIFT * 8; > + zone->pcp_batch = PAGE_SHIFT * 8; > } > > > @@ -3115,10 +3118,10 @@ static int __cpuinit process_zones(int cpu) > if (!zone_pcp(zone, cpu)) > goto bad; > > - setup_pageset(zone_pcp(zone, cpu), zone_batchsize(zone)); > + setup_pageset(zone, zone_pcp(zone, cpu), zone_batchsize(zone)); > > if (percpu_pagelist_fraction) > - setup_pagelist_highmark(zone_pcp(zone, cpu), > + setup_pagelist_highmark(zone, zone_pcp(zone, cpu), > (zone->present_pages / percpu_pagelist_fraction)); > } > > @@ -3250,7 +3253,7 @@ static int __zone_pcp_update(void *data) > > local_irq_save(flags); > free_pcppages_bulk(zone, pcp->count, pcp); > - setup_pageset(pset, batch); > + setup_pageset(zone, pset, batch); > local_irq_restore(flags); > } > return 0; > @@ -3270,9 +3273,9 @@ static __meminit void zone_pcp_init(struct zone *zone) > #ifdef CONFIG_NUMA > /* Early boot. Slab allocator not functional yet */ > zone_pcp(zone, cpu) = &boot_pageset[cpu]; > - setup_pageset(&boot_pageset[cpu],0); > + setup_pageset(zone, &boot_pageset[cpu],0); > #else > - setup_pageset(zone_pcp(zone,cpu), batch); > + setup_pageset(zone, zone_pcp(zone,cpu), batch); > #endif > } > if (zone->present_pages) > @@ -4781,7 +4784,7 @@ int lowmem_reserve_ratio_sysctl_handler(ctl_table *table, int write, > } > > /* > - * percpu_pagelist_fraction - changes the pcp->high for each zone on each > + * percpu_pagelist_fraction - changes the zone->pcp_high for each zone on each > * cpu. It is the fraction of total pages in each zone that a hot per cpu pagelist > * can have before it gets flushed back to buddy allocator. > */ > @@ -4800,7 +4803,7 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write, > for_each_online_cpu(cpu) { > unsigned long high; > high = zone->present_pages / percpu_pagelist_fraction; > - setup_pagelist_highmark(zone_pcp(zone, cpu), high); > + setup_pagelist_highmark(zone, zone_pcp(zone, cpu), high); > } > } > return 0; > diff --git a/mm/vmstat.c b/mm/vmstat.c > index c81321f..a9d23c3 100644 > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -746,8 +746,8 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat, > "\n batch: %i", > i, > pageset->pcp.count, > - pageset->pcp.high, > - pageset->pcp.batch); > + zone->pcp_high, > + zone->pcp_batch); > #ifdef CONFIG_SMP > seq_printf(m, "\n vm stats threshold: %d", > pageset->stat_threshold); > -- > 1.6.3.3
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