From: Michal Hocko <mhocko@suse.com>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org
Subject: Re: [PATCH] mm, page_alloc: cleanup usemap_size() when SPARSEMEM is not set
Date: Tue, 22 Jan 2019 16:16:28 +0100 [thread overview]
Message-ID: <20190122151628.GI4087@dhcp22.suse.cz> (raw)
In-Reply-To: <20190122150717.llf4owk6soejibov@master>
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@gmail.com>
> >> ---
> >> 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
next prev parent reply other threads:[~2019-01-22 15:16 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-18 23:49 [PATCH] mm, page_alloc: cleanup usemap_size() when SPARSEMEM is not set Wei Yang
2019-01-22 8:55 ` Michal Hocko
2019-01-22 15:07 ` Wei Yang
2019-01-22 15:16 ` Michal Hocko [this message]
2019-01-22 15:56 ` Wei Yang
2019-01-23 9:55 ` Michal Hocko
2019-01-24 14:13 ` Wei Yang
2019-01-24 14:30 ` Michal Hocko
2019-01-25 1:12 ` Wei Yang
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