Commit 4f44657d authored by Xunlei Pang's avatar Xunlei Pang Committed by Jens Axboe
Browse files

blk-cgroup: Fix the recursive blkg rwstat 



The current blkio.throttle.io_service_bytes_recursive doesn't
work correctly.

As an example, for the following blkcg hierarchy:
 (Made 1GB READ in test1, 512MB READ in test2)
     test
    /    \
 test1   test2

$ head -n 1 test/test1/blkio.throttle.io_service_bytes_recursive
8:0 Read 1073684480
$ head -n 1 test/test2/blkio.throttle.io_service_bytes_recursive
8:0 Read 537448448
$ head -n 1 test/blkio.throttle.io_service_bytes_recursive
8:0 Read 537448448

Clearly, above data of "test" reflects "test2" not "test1"+"test2".

Do the correct summary in blkg_rwstat_recursive_sum().

Signed-off-by: default avatarXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 66f669a2

block/blk-cgroup-rwstat.c

+2 −1
Original line number Diff line number Diff line
@@ -109,6 +109,7 @@ void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol, 


	lockdep_assert_held(&blkg->q->queue_lock);



	memset(sum, 0, sizeof(*sum));

	rcu_read_lock();

	blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {

		struct blkg_rwstat *rwstat;
@@ -122,7 +123,7 @@ void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol, 
			rwstat = (void *)pos_blkg + off;



		for (i = 0; i < BLKG_RWSTAT_NR; i++)

			sum->cnt[i] = blkg_rwstat_read_counter(rwstat, i);

			sum->cnt[i] += blkg_rwstat_read_counter(rwstat, i);

	}

	rcu_read_unlock();

}