Hi Barry Song:
> i'd call get_pcppage_migratetype() again in free_unref_page_commit()
> rather than adding a parameter to increase a couple cross functions.
It looks like the better coding.
I will submit the v2-patch if the optimization idea of patch is accepted
by maintainer.
Thank you very much.
lipeifeng@xxxxxxxx
From: Barry SongDate: 2022-04-24 12:34Subject: Re: [PATCH] mm/page_alloc: give priority to free cma-pages from pcplist to buddyOn Sun, Apr 24, 2022 at 3:28 PM <lipeifeng@xxxxxxxx> wrote:>> From: lipeifeng <lipeifeng@xxxxxxxx>>> Cma-pages will be fallback to movable pages in many scenarios.when cma> pages are freed to pcplist, we give priority to free it from pcplist> to buddy in order to avoids cma-pages to be used as movable-pages soon> if there is enough free-movable-pages, which saves more cma-pages in> buddy to decrease pages migration when cma_alloc.>> Signed-off-by: lipeifeng <lipeifeng@xxxxxxxx>> ---+ Christoph, Marek, Robin as it is cma-related.> mm/page_alloc.c | 28 ++++++++++++++++++++++++----> 1 file changed, 24 insertions(+), 4 deletions(-)>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c> index 3589feb..69369ed 100644> --- a/mm/page_alloc.c> +++ b/mm/page_alloc.c> @@ -3372,7 +3372,7 @@ static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone)> }>> static void free_unref_page_commit(struct page *page, unsigned long pfn,> - int migratetype, unsigned int order)> + int migratetype, unsigned int order, bool fast_free)> {> struct zone *zone = page_zone(page);> struct per_cpu_pages *pcp;> @@ -3382,7 +3382,10 @@ static void free_unref_page_commit(struct page *page, unsigned long pfn,> __count_vm_event(PGFREE);> pcp = this_cpu_ptr(zone->per_cpu_pageset);> pindex = order_to_pindex(migratetype, order);> - list_add(&page->lru, &pcp->lists[pindex]);> + if (fast_free)> + list_add_tail(&page->lru, &pcp->lists[pindex]);> + else> + list_add(&page->lru, &pcp->lists[pindex]);Ok. This is interesting, we used to have a separate cma pcp list butnow MIGRATE_CMA is an outsider so cma pages are placed in theMIGRATE_MOVABLE list.enum migratetype {MIGRATE_UNMOVABLE,MIGRATE_MOVABLE,MIGRATE_RECLAIMABLE,MIGRATE_PCPTYPES, /* the number of types on the pcp lists */MIGRATE_HIGHATOMIC = MIGRATE_PCPTYPES,#ifdef CONFIG_CMA...MIGRATE_CMA,#endif#ifdef CONFIG_MEMORY_ISOLATIONMIGRATE_ISOLATE, /* can't allocate from here */#endifMIGRATE_TYPES};#define NR_PCP_LISTS (MIGRATE_PCPTYPES * (PAGE_ALLOC_COSTLY_ORDER + 1+ NR_PCP_THP))> pcp->count += 1 << order;> high = nr_pcp_high(pcp, zone);> if (pcp->count >= high) {> @@ -3400,6 +3403,7 @@ void free_unref_page(struct page *page, unsigned int order)> unsigned long flags;> unsigned long pfn = page_to_pfn(page);> int migratetype;> + bool fast_free = false;>> if (!free_unref_page_prepare(page, pfn, order))> return;> @@ -3419,9 +3423,15 @@ void free_unref_page(struct page *page, unsigned int order)> }> migratetype = MIGRATE_MOVABLE;> }> + /*> + * Give priority to free cma-pages to buddy in order to> + * decrease pages migration when cma_alloc.> + */> + if (migratetype == MIGRATE_CMA)> + fast_free = true;>> local_lock_irqsave(&pagesets.lock, flags);> - free_unref_page_commit(page, pfn, migratetype, order);> + free_unref_page_commit(page, pfn, migratetype, order, fast_free);> local_unlock_irqrestore(&pagesets.lock, flags);> }>> @@ -3459,6 +3469,8 @@ void free_unref_page_list(struct list_head *list)>> local_lock_irqsave(&pagesets.lock, flags);> list_for_each_entry_safe(page, next, list, lru) {> + bool fast_free = false;> +> pfn = page_private(page);> set_page_private(page, 0);>> @@ -3467,11 +3479,19 @@ void free_unref_page_list(struct list_head *list)> * to the MIGRATE_MOVABLE pcp list.> */> migratetype = get_pcppage_migratetype(page);> +> + /*> + * Give priority to free cma-pages to buddy in order to> + * decrease pages migration when cma_alloc.> + */> + if (migratetype == MIGRATE_CMA)> + fast_free = true;> +> if (unlikely(migratetype >= MIGRATE_PCPTYPES))> migratetype = MIGRATE_MOVABLE;>> trace_mm_page_free_batched(page);> - free_unref_page_commit(page, pfn, migratetype, 0);> + free_unref_page_commit(page, pfn, migratetype, 0, fast_free);i'd call get_pcppage_migratetype() again in free_unref_page_commit()rather than adding a parameter to increase a couple cross functions.>> /*> * Guard against excessive IRQ disabled times when we get> --> 2.7.4>ThanksBarry
