On Thu 19-07-18 15:27:38, [email protected] wrote: > From: Oscar Salvador <[email protected]> > > In free_area_init_core we calculate the amount of managed pages > we are left with, by substracting the memmap pages and the pages > reserved for dma. > With the values left, we also account the total of kernel pages and > the total of pages. > > Since memmap pages are calculated from zone->spanned_pages, > let us only do these calculcations whenever zone->spanned_pages is greather > than 0.
But why do we care? How do we test this? In other words, why is this worth merging? > > Signed-off-by: Oscar Salvador <[email protected]> > --- > mm/page_alloc.c | 73 > ++++++++++++++++++++++++++++++--------------------------- > 1 file changed, 38 insertions(+), 35 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 10b754fba5fa..f7a6f4e13f41 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6237,6 +6237,40 @@ static void pgdat_init_kcompactd(struct pglist_data > *pgdat) > static void pgdat_init_kcompactd(struct pglist_data *pgdat) {} > #endif > > +static unsigned long calc_remaining_pages(enum zone_type type, unsigned long > freesize, > + unsigned long > size) > +{ > + unsigned long memmap_pages = calc_memmap_size(size, freesize); > + > + if(!is_highmem_idx(type)) { > + if (freesize >= memmap_pages) { > + freesize -= memmap_pages; > + if (memmap_pages) > + printk(KERN_DEBUG > + " %s zone: %lu pages used for > memmap\n", > + zone_names[type], memmap_pages); > + } else > + pr_warn(" %s zone: %lu pages exceeds freesize %lu\n", > + zone_names[type], memmap_pages, freesize); > + } > + > + /* Account for reserved pages */ > + if (type == 0 && freesize > dma_reserve) { > + freesize -= dma_reserve; > + printk(KERN_DEBUG " %s zone: %lu pages reserved\n", > + zone_names[0], dma_reserve); > + } > + > + if (!is_highmem_idx(type)) > + nr_kernel_pages += freesize; > + /* Charge for highmem memmap if there are enough kernel pages */ > + else if (nr_kernel_pages > memmap_pages * 2) > + nr_kernel_pages -= memmap_pages; > + nr_all_pages += freesize; > + > + return freesize; > +} > + > /* > * Set up the zone data structures: > * - mark all pages reserved > @@ -6267,43 +6301,12 @@ static void __paginginit free_area_init_core(struct > pglist_data *pgdat) > > for (j = 0; j < MAX_NR_ZONES; j++) { > struct zone *zone = pgdat->node_zones + j; > - unsigned long size, freesize, memmap_pages; > + unsigned long size = zone->spanned_pages; > + unsigned long freesize = zone->present_pages; > unsigned long zone_start_pfn = zone->zone_start_pfn; > > - size = zone->spanned_pages; > - freesize = zone->present_pages; > - > - /* > - * Adjust freesize so that it accounts for how much memory > - * is used by this zone for memmap. This affects the watermark > - * and per-cpu initialisations > - */ > - memmap_pages = calc_memmap_size(size, freesize); > - if (!is_highmem_idx(j)) { > - if (freesize >= memmap_pages) { > - freesize -= memmap_pages; > - if (memmap_pages) > - printk(KERN_DEBUG > - " %s zone: %lu pages used for > memmap\n", > - zone_names[j], memmap_pages); > - } else > - pr_warn(" %s zone: %lu pages exceeds freesize > %lu\n", > - zone_names[j], memmap_pages, freesize); > - } > - > - /* Account for reserved pages */ > - if (j == 0 && freesize > dma_reserve) { > - freesize -= dma_reserve; > - printk(KERN_DEBUG " %s zone: %lu pages reserved\n", > - zone_names[0], dma_reserve); > - } > - > - if (!is_highmem_idx(j)) > - nr_kernel_pages += freesize; > - /* Charge for highmem memmap if there are enough kernel pages */ > - else if (nr_kernel_pages > memmap_pages * 2) > - nr_kernel_pages -= memmap_pages; > - nr_all_pages += freesize; > + if (size) > + freesize = calc_remaining_pages(j, freesize, size); > > /* > * Set an approximate value for lowmem here, it will be adjusted > -- > 2.13.6 > -- Michal Hocko SUSE Labs
