| Message ID | 20220217002227.5739-5-mgorman@techsingularity.net (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Follow-up on high-order PCP caching | expand |
On 2/17/22 01:22, Mel Gorman wrote: > Prior to the series, pindex 0 (order-0 MIGRATE_UNMOVABLE) was always > skipped first and the precise reason is forgotten. A potential reason may > have been to artificially preserve MIGRATE_UNMOVABLE but there is no reason > why that would be optimal as it depends on the workload. The more likely > reason is that it was less complicated to do a pre-increment instead of > a post-increment in terms of overall code flow. As free_pcppages_bulk() > now typically receives the pindex of the PCP list that exceeded high, > always start draining that list. > > Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/page_alloc.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index dfc347a58ea6..635a4e0f70b4 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1463,6 +1463,10 @@ static void free_pcppages_bulk(struct zone *zone, int count, > * below while (list_empty(list)) loop. > */ > count = min(pcp->count, count); > + > + /* Ensure requested pindex is drained first. */ > + pindex = pindex - 1; > + > while (count > 0) { > struct list_head *list; > int nr_pages;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index dfc347a58ea6..635a4e0f70b4 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1463,6 +1463,10 @@ static void free_pcppages_bulk(struct zone *zone, int count, * below while (list_empty(list)) loop. */ count = min(pcp->count, count); + + /* Ensure requested pindex is drained first. */ + pindex = pindex - 1; + while (count > 0) { struct list_head *list; int nr_pages;
Prior to the series, pindex 0 (order-0 MIGRATE_UNMOVABLE) was always skipped first and the precise reason is forgotten. A potential reason may have been to artificially preserve MIGRATE_UNMOVABLE but there is no reason why that would be optimal as it depends on the workload. The more likely reason is that it was less complicated to do a pre-increment instead of a post-increment in terms of overall code flow. As free_pcppages_bulk() now typically receives the pindex of the PCP list that exceeded high, always start draining that list. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> --- mm/page_alloc.c | 4 ++++ 1 file changed, 4 insertions(+)