mm/page_alloc: use only one PCP list for THP-sized allocations
The per_cpu_pages is cache-aligned on a standard x86-64 distribution
configuration but a later patch will add a new field which would push the
structure into the next cache line. Use only one list to store THP-sized
pages on the per-cpu list. This assumes that the vast majority of
THP-sized allocations are GFP_MOVABLE but even if it was another type, it
would not contribute to serious fragmentation that potentially causes a
later THP allocation failure. Align per_cpu_pages on the cacheline
boundary to ensure there is no false cache sharing.
After this patch, the structure sizing is;
struct per_cpu_pages {
int count; /* 0 4 */
int high; /* 4 4 */
int batch; /* 8 4 */
short int free_factor; /* 12 2 */
short int expire; /* 14 2 */
struct list_head lists[13]; /* 16 208 */
/* size: 256, cachelines: 4, members: 6 */
/* padding: 32 */
} __attribute__((__aligned__(64)));
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mel Gorman <[email protected]>
Tested-by: Minchan Kim <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Nicolas Saenz Julienne <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
2 files changed
