writeback: implement memcg wb_domain

Dirtyable memory is distributed to a wb (bdi_writeback) according to
the relative bandwidth the wb is writing out in the whole system.
This distribution is global - each wb is measured against all other
wb's and gets the proportinately sized portion of the memory in the
whole system.

For cgroup writeback, the amount of dirtyable memory is scoped by
memcg and thus each wb would need to be measured and controlled in its
memcg.  IOW, a wb will belong to two writeback domains - the global
and memcg domains.

The previous patches laid the groundwork to support the two wb_domains
and this patch implements memcg wb_domain.  memcg->cgwb_domain is
initialized on css online and destroyed on css release,
wb->memcg_completions is added, and __wb_writeout_inc() is updated to
increment completions against both global and memcg wb_domains.

The following patches will update balance_dirty_pages() and its
subroutines to actually consider memcg wb_domain for throttling.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
index 97a92fa0cdb59900c0d216a867bc6c5d2a0c2ab1..8d470b73824f2d89e1ee7065a9c5cc7b2c4c5e65 100644 (file)
--- a/include/linux/backing-dev-defs.h
+++ b/include/linux/backing-dev-defs.h
@@ -118,6 +118,7 @@ struct bdi_writeback {
 
 #ifdef CONFIG_CGROUP_WRITEBACK
        struct percpu_ref refcnt;       /* used only for !root wb's */
+       struct fprop_local_percpu memcg_completions;
        struct cgroup_subsys_state *memcg_css; /* the associated memcg */
        struct cgroup_subsys_state *blkcg_css; /* and blkcg */
        struct list_head memcg_node;    /* anchored at memcg->cgwb_list */

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 662a953ea8ad200fbbbe26388d7878a86ce14ba8..e3177bed23ea61389889848b192e738c3f029d26 100644 (file)
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -389,8 +389,18 @@ enum {
 };
 
 #ifdef CONFIG_CGROUP_WRITEBACK
+
 struct list_head *mem_cgroup_cgwb_list(struct mem_cgroup *memcg);
-#endif
+struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb);
+
+#else  /* CONFIG_CGROUP_WRITEBACK */
+
+static inline struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb)
+{
+       return NULL;
+}
+
+#endif /* CONFIG_CGROUP_WRITEBACK */
 
 struct sock;
 #if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)

diff --cc include/linux/writeback.h
Simple merge

diff --cc mm/backing-dev.c
Simple merge

diff --cc mm/memcontrol.c
Simple merge

diff --cc mm/page-writeback.c
Simple merge