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Date: Wed, 10 Apr 2013 11:23:33 -0700 From: Cody P Schafer <cody@...ux.vnet.ibm.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: Gilad Ben-Yossef <gilad@...yossef.com>, Simon Jeons <simon.jeons@...il.com>, KOSAKI Motohiro <kosaki.motohiro@...il.com>, Mel Gorman <mgorman@...e.de>, Linux MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>, Cody P Schafer <cody@...ux.vnet.ibm.com> Subject: [PATCH v3 05/11] mm/page_alloc: convert zone_pcp_update() to rely on memory barriers instead of stop_machine() zone_pcp_update()'s goal is to adjust the ->high and ->mark members of a percpu pageset based on a zone's ->managed_pages. We don't need to drain the entire percpu pageset just to modify these fields. This lets us avoid calling setup_pageset() (and the draining required to call it) and instead allows simply setting the fields' values (with some attention paid to memory barriers to prevent the relationship between ->batch and ->high from being thrown off). This does change the behavior of zone_pcp_update() as the percpu pagesets will not be drained when zone_pcp_update() is called (they will end up being shrunk, not completely drained, later when a 0-order page is freed in free_hot_cold_page()). Signed-off-by: Cody P Schafer <cody@...ux.vnet.ibm.com> --- mm/page_alloc.c | 33 +++++++++------------------------ 1 file changed, 9 insertions(+), 24 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 9dd0dc0..5c54a08 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6019,33 +6019,18 @@ void free_contig_range(unsigned long pfn, unsigned nr_pages) #endif #ifdef CONFIG_MEMORY_HOTPLUG -static int __meminit __zone_pcp_update(void *data) -{ - struct zone *zone = data; - int cpu; - unsigned long batch = zone_batchsize(zone), flags; - - for_each_possible_cpu(cpu) { - struct per_cpu_pageset *pset; - struct per_cpu_pages *pcp; - - pset = per_cpu_ptr(zone->pageset, cpu); - pcp = &pset->pcp; - - local_irq_save(flags); - if (pcp->count > 0) - free_pcppages_bulk(zone, pcp->count, pcp); - drain_zonestat(zone, pset); - setup_pageset(pset, batch); - local_irq_restore(flags); - } - return 0; -} - +/* + * The zone indicated has a new number of managed_pages; batch sizes and percpu + * page high values need to be recalulated. + */ void __meminit zone_pcp_update(struct zone *zone) { + unsigned cpu; + unsigned long batch; mutex_lock(&pcp_batch_high_lock); - stop_machine(__zone_pcp_update, zone, NULL); + batch = zone_batchsize(zone); + for_each_possible_cpu(cpu) + pageset_set_batch(per_cpu_ptr(zone->pageset, cpu), batch); mutex_unlock(&pcp_batch_high_lock); } #endif -- 1.8.2.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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