* [PATCH] mm/page_alloc: cleanup __alloc_pages_direct_compact()
@ 2019-08-17 10:51 Pengfei Li
2019-08-19 13:50 ` Vlastimil Babka
0 siblings, 1 reply; 3+ messages in thread
From: Pengfei Li @ 2019-08-17 10:51 UTC (permalink / raw)
To: akpm
Cc: mhocko, vbabka, osalvador, pavel.tatashin, mgorman, linux-mm,
linux-kernel, Pengfei Li
This patch cleans up the if(page).
No functional change.
Signed-off-by: Pengfei Li <lpf.vector@gmail.com>
---
mm/page_alloc.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 272c6de1bf4e..51f056ac09f5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3890,6 +3890,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
enum compact_priority prio, enum compact_result *compact_result)
{
struct page *page = NULL;
+ struct zone *zone;
unsigned long pflags;
unsigned int noreclaim_flag;
@@ -3911,23 +3912,26 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
*/
count_vm_event(COMPACTSTALL);
- /* Prep a captured page if available */
- if (page)
+ if (page) {
+ /* Prep a captured page if available */
prep_new_page(page, order, gfp_mask, alloc_flags);
-
- /* Try get a page from the freelist if available */
- if (!page)
+ } else {
+ /* Try get a page from the freelist if available */
page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
- if (page) {
- struct zone *zone = page_zone(page);
-
- zone->compact_blockskip_flush = false;
- compaction_defer_reset(zone, order, true);
- count_vm_event(COMPACTSUCCESS);
- return page;
+ if (!page)
+ goto failed;
}
+ zone = page_zone(page);
+ zone->compact_blockskip_flush = false;
+ compaction_defer_reset(zone, order, true);
+
+ count_vm_event(COMPACTSUCCESS);
+
+ return page;
+
+failed:
/*
* It's bad if compaction run occurs and fails. The most likely reason
* is that pages exist, but not enough to satisfy watermarks.
--
2.21.0
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] mm/page_alloc: cleanup __alloc_pages_direct_compact()
2019-08-17 10:51 [PATCH] mm/page_alloc: cleanup __alloc_pages_direct_compact() Pengfei Li
@ 2019-08-19 13:50 ` Vlastimil Babka
2019-08-19 15:29 ` Pengfei Li
0 siblings, 1 reply; 3+ messages in thread
From: Vlastimil Babka @ 2019-08-19 13:50 UTC (permalink / raw)
To: Pengfei Li, akpm
Cc: mhocko, osalvador, pavel.tatashin, mgorman, linux-mm, linux-kernel
On 8/17/19 12:51 PM, Pengfei Li wrote:
> This patch cleans up the if(page).
>
> No functional change.
>
> Signed-off-by: Pengfei Li <lpf.vector@gmail.com>
I don't see much benefit here. The indentation wasn't that bad that it
had to be reduced using goto. But the patch is not incorrect so I'm not
NACKing.
> ---
> mm/page_alloc.c | 28 ++++++++++++++++------------
> 1 file changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 272c6de1bf4e..51f056ac09f5 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3890,6 +3890,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> enum compact_priority prio, enum compact_result *compact_result)
> {
> struct page *page = NULL;
> + struct zone *zone;
> unsigned long pflags;
> unsigned int noreclaim_flag;
>
> @@ -3911,23 +3912,26 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> */
> count_vm_event(COMPACTSTALL);
>
> - /* Prep a captured page if available */
> - if (page)
> + if (page) {
> + /* Prep a captured page if available */
> prep_new_page(page, order, gfp_mask, alloc_flags);
> -
> - /* Try get a page from the freelist if available */
> - if (!page)
> + } else {
> + /* Try get a page from the freelist if available */
> page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
>
> - if (page) {
> - struct zone *zone = page_zone(page);
> -
> - zone->compact_blockskip_flush = false;
> - compaction_defer_reset(zone, order, true);
> - count_vm_event(COMPACTSUCCESS);
> - return page;
> + if (!page)
> + goto failed;
> }
>
> + zone = page_zone(page);
> + zone->compact_blockskip_flush = false;
> + compaction_defer_reset(zone, order, true);
> +
> + count_vm_event(COMPACTSUCCESS);
> +
> + return page;
> +
> +failed:
> /*
> * It's bad if compaction run occurs and fails. The most likely reason
> * is that pages exist, but not enough to satisfy watermarks.
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] mm/page_alloc: cleanup __alloc_pages_direct_compact()
2019-08-19 13:50 ` Vlastimil Babka
@ 2019-08-19 15:29 ` Pengfei Li
0 siblings, 0 replies; 3+ messages in thread
From: Pengfei Li @ 2019-08-19 15:29 UTC (permalink / raw)
To: Vlastimil Babka
Cc: Andrew Morton, mhocko, osalvador, pavel.tatashin, Mel Gorman,
linux-mm, linux-kernel
On Mon, Aug 19, 2019 at 9:50 PM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 8/17/19 12:51 PM, Pengfei Li wrote:
> > This patch cleans up the if(page).
> >
> > No functional change.
> >
> > Signed-off-by: Pengfei Li <lpf.vector@gmail.com>
>
> I don't see much benefit here. The indentation wasn't that bad that it
> had to be reduced using goto. But the patch is not incorrect so I'm not
> NACKing.
>
Thanks for your review and comments.
This patch reduces the number of times the if(page)
(as the compiler does), and the downside is that there is a goto.
If this improves readability, accept it. Otherwise, leave it as it is.
Thanks again.
---
Pengfei
> > ---
> > mm/page_alloc.c | 28 ++++++++++++++++------------
> > 1 file changed, 16 insertions(+), 12 deletions(-)
> >
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 272c6de1bf4e..51f056ac09f5 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -3890,6 +3890,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> > enum compact_priority prio, enum compact_result *compact_result)
> > {
> > struct page *page = NULL;
> > + struct zone *zone;
> > unsigned long pflags;
> > unsigned int noreclaim_flag;
> >
> > @@ -3911,23 +3912,26 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> > */
> > count_vm_event(COMPACTSTALL);
> >
> > - /* Prep a captured page if available */
> > - if (page)
> > + if (page) {
> > + /* Prep a captured page if available */
> > prep_new_page(page, order, gfp_mask, alloc_flags);
> > -
> > - /* Try get a page from the freelist if available */
> > - if (!page)
> > + } else {
> > + /* Try get a page from the freelist if available */
> > page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
> >
> > - if (page) {
> > - struct zone *zone = page_zone(page);
> > -
> > - zone->compact_blockskip_flush = false;
> > - compaction_defer_reset(zone, order, true);
> > - count_vm_event(COMPACTSUCCESS);
> > - return page;
> > + if (!page)
> > + goto failed;
> > }
> >
> > + zone = page_zone(page);
> > + zone->compact_blockskip_flush = false;
> > + compaction_defer_reset(zone, order, true);
> > +
> > + count_vm_event(COMPACTSUCCESS);
> > +
> > + return page;
> > +
> > +failed:
> > /*
> > * It's bad if compaction run occurs and fails. The most likely reason
> > * is that pages exist, but not enough to satisfy watermarks.
> >
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-08-17 10:51 [PATCH] mm/page_alloc: cleanup __alloc_pages_direct_compact() Pengfei Li
2019-08-19 13:50 ` Vlastimil Babka
2019-08-19 15:29 ` Pengfei Li
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