Re: [PATCH 1/2] mm/sparse: pass the __highest_present_section_nr + 1 to alloc_func()

[David Rientjes <rientjes@google.com>]

On Tue, 27 Mar 2018, Wei Yang wrote:

> >> In 'commit c4e1be9ec113 ("mm, sparsemem: break out of loops early")',
> >> __highest_present_section_nr is introduced to reduce the loop counts for
> >> present section. This is also helpful for usemap and memmap allocation.
> >> 
> >> This patch uses __highest_present_section_nr + 1 to optimize the loop.
> >> 
> >> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
> >> ---
> >>  mm/sparse.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> 
> >> diff --git a/mm/sparse.c b/mm/sparse.c
> >> index 7af5e7a92528..505050346249 100644
> >> --- a/mm/sparse.c
> >> +++ b/mm/sparse.c
> >> @@ -561,7 +561,7 @@ static void __init alloc_usemap_and_memmap(void (*alloc_func)
> >>  		map_count = 1;
> >>  	}
> >>  	/* ok, last chunk */
> >> -	alloc_func(data, pnum_begin, NR_MEM_SECTIONS,
> >> +	alloc_func(data, pnum_begin, __highest_present_section_nr+1,
> >>  						map_count, nodeid_begin);
> >>  }
> >>  
> >
> >What happens if s/NR_MEM_SECTIONS/pnum/?
> 
> I have tried this :-)
> 
> The last pnum is -1 from next_present_section_nr().
> 

Lol.  I think it would make more sense for the second patch to come before 
the first, but feel free to add

Acked-by: David Rientjes <rientjes@google.com>