* [PATCH] mm/highmem: simplify is_highmem()
@ 2016-03-30 4:43 Chanho Min
2016-03-30 6:34 ` Dan Williams
2016-03-30 9:24 ` Michal Hocko
0 siblings, 2 replies; 4+ messages in thread
From: Chanho Min @ 2016-03-30 4:43 UTC (permalink / raw)
To: Andrew Morton, Mel Gorman, Vlastimil Babka, David Rientjes,
Michal Hocko, Dan Williams, Zhang Zhen
Cc: linux-mm, linux-kernel, Gunho Lee, Chanho Min
The is_highmem() is can be simplified by use of is_highmem_idx().
This patch removes redundant code and will make it easier to maintain
if the zone policy is changed or a new zone is added.
Signed-off-by: Chanho Min <chanho.min@lge.com>
---
include/linux/mmzone.h | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index e23a9e7..9ac90c3 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -817,10 +817,7 @@ static inline int is_highmem_idx(enum zone_type idx)
static inline int is_highmem(struct zone *zone)
{
#ifdef CONFIG_HIGHMEM
- int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
- return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
- (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
- zone_movable_is_highmem());
+ return is_highmem_idx(zone_idx(zone));
#else
return 0;
#endif
--
1.7.9.5
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] mm/highmem: simplify is_highmem()
2016-03-30 4:43 [PATCH] mm/highmem: simplify is_highmem() Chanho Min
@ 2016-03-30 6:34 ` Dan Williams
2016-03-30 9:24 ` Michal Hocko
1 sibling, 0 replies; 4+ messages in thread
From: Dan Williams @ 2016-03-30 6:34 UTC (permalink / raw)
To: Chanho Min
Cc: Andrew Morton, Mel Gorman, Vlastimil Babka, David Rientjes,
Michal Hocko, Zhang Zhen, Linux MM, linux-kernel, Gunho Lee
On Tue, Mar 29, 2016 at 9:43 PM, Chanho Min <chanho.min@lge.com> wrote:
> The is_highmem() is can be simplified by use of is_highmem_idx().
> This patch removes redundant code and will make it easier to maintain
> if the zone policy is changed or a new zone is added.
>
> Signed-off-by: Chanho Min <chanho.min@lge.com>
> ---
> include/linux/mmzone.h | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index e23a9e7..9ac90c3 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -817,10 +817,7 @@ static inline int is_highmem_idx(enum zone_type idx)
> static inline int is_highmem(struct zone *zone)
> {
> #ifdef CONFIG_HIGHMEM
> - int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
> - return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
> - (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
> - zone_movable_is_highmem());
> + return is_highmem_idx(zone_idx(zone));
> #else
> return 0;
> #endif
Yup, looks like a straightforward replacement of open coded versions
of the same routines.
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] mm/highmem: simplify is_highmem()
2016-03-30 4:43 [PATCH] mm/highmem: simplify is_highmem() Chanho Min
2016-03-30 6:34 ` Dan Williams
@ 2016-03-30 9:24 ` Michal Hocko
2016-03-31 22:38 ` Andrew Morton
1 sibling, 1 reply; 4+ messages in thread
From: Michal Hocko @ 2016-03-30 9:24 UTC (permalink / raw)
To: Chanho Min
Cc: Andrew Morton, Mel Gorman, Vlastimil Babka, David Rientjes,
Dan Williams, Zhang Zhen, linux-mm, linux-kernel, Gunho Lee
On Wed 30-03-16 13:43:42, Chanho Min wrote:
> The is_highmem() is can be simplified by use of is_highmem_idx().
> This patch removes redundant code and will make it easier to maintain
> if the zone policy is changed or a new zone is added.
>
> Signed-off-by: Chanho Min <chanho.min@lge.com>
> ---
> include/linux/mmzone.h | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index e23a9e7..9ac90c3 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -817,10 +817,7 @@ static inline int is_highmem_idx(enum zone_type idx)
> static inline int is_highmem(struct zone *zone)
> {
> #ifdef CONFIG_HIGHMEM
> - int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
> - return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
> - (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
> - zone_movable_is_highmem());
> + return is_highmem_idx(zone_idx(zone));
This will reintroduce the pointer arithmetic removed by ddc81ed2c5d4
("remove sparse warning for mmzone.h") AFAICS. I have no idea how much
that matters though. The mentioned commit doesn't tell much about saves
except for
"
On X86_32 this saves a sar, but code size increases by one byte per
is_highmem() use due to 32-bit cmps rather than 16 bit cmps.
"
> #else
> return 0;
> #endif
> --
> 1.7.9.5
>
--
Michal Hocko
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] mm/highmem: simplify is_highmem()
2016-03-30 9:24 ` Michal Hocko
@ 2016-03-31 22:38 ` Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2016-03-31 22:38 UTC (permalink / raw)
To: Michal Hocko
Cc: Chanho Min, Mel Gorman, Vlastimil Babka, David Rientjes,
Dan Williams, Zhang Zhen, linux-mm, linux-kernel, Gunho Lee
On Wed, 30 Mar 2016 11:24:38 +0200 Michal Hocko <mhocko@kernel.org> wrote:
> On Wed 30-03-16 13:43:42, Chanho Min wrote:
> > The is_highmem() is can be simplified by use of is_highmem_idx().
> > This patch removes redundant code and will make it easier to maintain
> > if the zone policy is changed or a new zone is added.
> >
> > Signed-off-by: Chanho Min <chanho.min@lge.com>
> > ---
> > include/linux/mmzone.h | 5 +----
> > 1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> > index e23a9e7..9ac90c3 100644
> > --- a/include/linux/mmzone.h
> > +++ b/include/linux/mmzone.h
> > @@ -817,10 +817,7 @@ static inline int is_highmem_idx(enum zone_type idx)
> > static inline int is_highmem(struct zone *zone)
> > {
> > #ifdef CONFIG_HIGHMEM
> > - int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
> > - return zone_off == ZONE_HIGHMEM * sizeof(*zone) ||
> > - (zone_off == ZONE_MOVABLE * sizeof(*zone) &&
> > - zone_movable_is_highmem());
> > + return is_highmem_idx(zone_idx(zone));
>
> This will reintroduce the pointer arithmetic removed by ddc81ed2c5d4
> ("remove sparse warning for mmzone.h") AFAICS. I have no idea how much
> that matters though. The mentioned commit doesn't tell much about saves
> except for
> "
> On X86_32 this saves a sar, but code size increases by one byte per
> is_highmem() use due to 32-bit cmps rather than 16 bit cmps.
> "
The patch shrinks my i386 allmodconfig page_alloc.o by 50 bytes, and
that has just two is_highmem() callsites. So I think it's OK from a
code-size and performance piont of view
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-03-31 22:38 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-03-30 4:43 [PATCH] mm/highmem: simplify is_highmem() Chanho Min
2016-03-30 6:34 ` Dan Williams
2016-03-30 9:24 ` Michal Hocko
2016-03-31 22:38 ` Andrew Morton
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox