On Sat 19-01-19 07:49:05, Wei Yang wrote: > Two cleanups in this patch: > > * since pageblock_nr_pages == (1 << pageblock_order), the roundup() > and right shift pageblock_order could be replaced with > DIV_ROUND_UP() Why is this change worth it? > * use BITS_TO_LONGS() to get number of bytes for bitmap > > This patch also fix one typo in comment. > > Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx> > --- > mm/page_alloc.c | 9 +++------ > 1 file changed, 3 insertions(+), 6 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d295c9bc01a8..d7073cedd087 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6352,7 +6352,7 @@ static void __init calculate_node_totalpages(struct pglist_data *pgdat, > /* > * Calculate the size of the zone->blockflags rounded to an unsigned long > * Start by making sure zonesize is a multiple of pageblock_order by rounding > - * up. Then use 1 NR_PAGEBLOCK_BITS worth of bits per pageblock, finally > + * up. Then use 1 NR_PAGEBLOCK_BITS width of bits per pageblock, finally why do you change this? > * round what is now in bits to nearest long in bits, then return it in > * bytes. > */ > @@ -6361,12 +6361,9 @@ static unsigned long __init usemap_size(unsigned long zone_start_pfn, unsigned l > unsigned long usemapsize; > > zonesize += zone_start_pfn & (pageblock_nr_pages-1); > - usemapsize = roundup(zonesize, pageblock_nr_pages); > - usemapsize = usemapsize >> pageblock_order; > + usemapsize = DIV_ROUND_UP(zonesize, pageblock_nr_pages); > usemapsize *= NR_PAGEBLOCK_BITS; > - usemapsize = roundup(usemapsize, 8 * sizeof(unsigned long)); > - > - return usemapsize / 8; > + return BITS_TO_LONGS(usemapsize) * sizeof(unsigned long); > } > > static void __ref setup_usemap(struct pglist_data *pgdat, > -- > 2.15.1 > -- Michal Hocko SUSE Labs
