On Tue 22-01-19 15:07:17, Wei Yang wrote: > On Tue, Jan 22, 2019 at 09:55:24AM +0100, Michal Hocko wrote: > >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? > > > > To make it directly show usemapsize is number of times of > pageblock_nr_pages. Does this lead to a better code generation? Does it make the code easier to read/maintain? > >> * 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? > > > > Is the original comment not correct? Or I misunderstand the English > word? yes AFAICS -- Michal Hocko SUSE Labs
