writeback: implement backing_dev_info->tot_write_bandwidth
cgroup writeback support needs to keep track of the sum of
avg_write_bandwidth of all wb's (bdi_writeback's) with dirty inodes to
distribute write workload. This patch adds bdi->tot_write_bandwidth
and updates inode_wb_list_move_locked(), inode_wb_list_del_locked()
and wb_update_write_bandwidth() to adjust it as wb's gain and lose
dirty inodes and its avg_write_bandwidth gets updated.
As the update events are not synchronized with each other,
bdi->tot_write_bandwidth is an atomic_long_t.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit 766a9d6e60578f1ef6de71f89f022084f8bffc82)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 0a90dc55..bbccf68 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -99,6 +99,8 @@
return false;
} else {
set_bit(WB_has_dirty_io, &wb->state);
+ atomic_long_add(wb->avg_write_bandwidth,
+ &wb->bdi->tot_write_bandwidth);
return true;
}
}
@@ -106,8 +108,11 @@
static void wb_io_lists_depopulated(struct bdi_writeback *wb)
{
if (wb_has_dirty_io(wb) && list_empty(&wb->b_dirty) &&
- list_empty(&wb->b_io) && list_empty(&wb->b_more_io))
+ list_empty(&wb->b_io) && list_empty(&wb->b_more_io)) {
clear_bit(WB_has_dirty_io, &wb->state);
+ atomic_long_sub(wb->avg_write_bandwidth,
+ &wb->bdi->tot_write_bandwidth);
+ }
}
/**
diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
index 7a94b78..d631a61 100644
--- a/include/linux/backing-dev-defs.h
+++ b/include/linux/backing-dev-defs.h
@@ -142,6 +142,8 @@
unsigned int min_ratio;
unsigned int max_ratio, max_prop_frac;
+ atomic_long_t tot_write_bandwidth; /* sum of active avg_write_bw */
+
struct bdi_writeback wb; /* the root writeback info for this bdi */
struct bdi_writeback_congested wb_congested; /* its congested state */
#ifdef CONFIG_CGROUP_WRITEBACK
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 55b77c6..05b779d 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -881,6 +881,9 @@
avg += (old - avg) >> 3;
out:
+ if (wb_has_dirty_io(wb))
+ atomic_long_add(avg - wb->avg_write_bandwidth,
+ &wb->bdi->tot_write_bandwidth);
wb->write_bandwidth = bw;
wb->avg_write_bandwidth = avg;
}