On Fri, Jul 08, 2016 at 10:34:38AM +0100, Mel Gorman wrote:
> Node-based reclaim requires node-based LRUs and locking. This is a
> preparation patch that just moves the lru_lock to the node so later
> patches are easier to review. It is a mechanical change but note this
> patch makes contention worse because the LRU lock is hotter and direct
> reclaim and kswapd can contend on the same lock even when reclaiming from
> different zones.
>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> Reviewed-by: Minchan Kim <minchan@xxxxxxxxxx>
> ---
> Documentation/cgroup-v1/memcg_test.txt | 4 +--
> Documentation/cgroup-v1/memory.txt | 4 +--
> include/linux/mm_types.h | 2 +-
> include/linux/mmzone.h | 10 +++++--
> mm/compaction.c | 10 +++----
> mm/filemap.c | 4 +--
> mm/huge_memory.c | 6 ++---
> mm/memcontrol.c | 6 ++---
> mm/mlock.c | 10 +++----
> mm/page_alloc.c | 4 +--
> mm/page_idle.c | 4 +--
> mm/rmap.c | 2 +-
> mm/swap.c | 30 ++++++++++-----------
> mm/vmscan.c | 48 +++++++++++++++++-----------------
> 14 files changed, 75 insertions(+), 69 deletions(-)
>
> diff --git a/Documentation/cgroup-v1/memcg_test.txt b/Documentation/cgroup-v1/memcg_test.txt
> index 8870b0212150..78a8c2963b38 100644
> --- a/Documentation/cgroup-v1/memcg_test.txt
> +++ b/Documentation/cgroup-v1/memcg_test.txt
> @@ -107,9 +107,9 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
>
> 8. LRU
> Each memcg has its own private LRU. Now, its handling is under global
> - VM's control (means that it's handled under global zone->lru_lock).
> + VM's control (means that it's handled under global zone_lru_lock).
> Almost all routines around memcg's LRU is called by global LRU's
> - list management functions under zone->lru_lock().
> + list management functions under zone_lru_lock().
>
> A special function is mem_cgroup_isolate_pages(). This scans
> memcg's private LRU and call __isolate_lru_page() to extract a page
> diff --git a/Documentation/cgroup-v1/memory.txt b/Documentation/cgroup-v1/memory.txt
> index b14abf217239..946e69103cdd 100644
> --- a/Documentation/cgroup-v1/memory.txt
> +++ b/Documentation/cgroup-v1/memory.txt
> @@ -267,11 +267,11 @@ When oom event notifier is registered, event will be delivered.
> Other lock order is following:
> PG_locked.
> mm->page_table_lock
> - zone->lru_lock
> + zone_lru_lock
zone_lru_lock is a little confusing, can't we just call it
node_lru_lock?
> lock_page_cgroup.
> In many cases, just lock_page_cgroup() is called.
> per-zone-per-cgroup LRU (cgroup's private LRU) is just guarded by
> - zone->lru_lock, it has no lock of its own.
> + zone_lru_lock, it has no lock of its own.
>
> 2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM)
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index e093e1d3285b..ca2ed9a6c8d8 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -118,7 +118,7 @@ struct page {
> */
> union {
> struct list_head lru; /* Pageout list, eg. active_list
> - * protected by zone->lru_lock !
> + * protected by zone_lru_lock !
> * Can be used as a generic list
> * by the page owner.
> */
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 078ecb81e209..cfa870107abe 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -93,7 +93,7 @@ struct free_area {
> struct pglist_data;
>
> /*
> - * zone->lock and zone->lru_lock are two of the hottest locks in the kernel.
> + * zone->lock and the zone lru_lock are two of the hottest locks in the kernel.
> * So add a wild amount of padding here to ensure that they fall into separate
> * cachelines. There are very few zone structures in the machine, so space
> * consumption is not a concern here.
> @@ -496,7 +496,6 @@ struct zone {
> /* Write-intensive fields used by page reclaim */
>
> /* Fields commonly accessed by the page reclaim scanner */
> - spinlock_t lru_lock;
> struct lruvec lruvec;
>
> /*
> @@ -690,6 +689,9 @@ typedef struct pglist_data {
> /* Number of pages migrated during the rate limiting time interval */
> unsigned long numabalancing_migrate_nr_pages;
> #endif
> + /* Write-intensive fields used by page reclaim */
> + ZONE_PADDING(_pad1_)a
I thought this was to have zone->lock and zone->lru_lock in different
cachelines, do we still need the padding here?
> + spinlock_t lru_lock;
>
Balbir Singh.
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