From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754269AbbJVAbM (ORCPT ); Wed, 21 Oct 2015 20:31:12 -0400 Received: from mail-pa0-f51.google.com ([209.85.220.51]:36755 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752975AbbJVAbK (ORCPT ); Wed, 21 Oct 2015 20:31:10 -0400 Date: Thu, 22 Oct 2015 09:31:03 +0900 From: Tejun Heo To: Jens Axboe Cc: Vivek Goyal , linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH block/for-4.4/core] blkcg: don't create "io.stat" on the root cgroup Message-ID: <20151022003103.GB10199@mtj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Jens. This is one of hopefully final adjustments to cgroup v2 behavior before lifting the devel mask. If the patch is okay, can I route the patch through cgroup/for-4.4 so that it can go together with the cgroup documentation update patch? Thanks. ------ 8< ------ The stat files on the root cgroup shows stats for the whole system and usually don't contain any information which isn't available through the usual system monitoring mechanisms. Some controllers skip collecting these duplicate stats to optimize cases where cgroup isn't used and later try to emulate the result on demand. This leads to complexities and subtle differences in the information shown through different channels. This is entirely unnecessary and cgroup v2 is dropping stat files which are duplicate from all controllers. This patch removes "io.stat" from the root hierarchy. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Vivek Goyal --- block/blk-cgroup.c | 1 + 1 file changed, 1 insertion(+) --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -896,6 +896,7 @@ static int blkcg_print_stat(struct seq_f struct cftype blkcg_files[] = { { .name = "stat", + .flags = CFTYPE_NOT_ON_ROOT, .seq_show = blkcg_print_stat, }, { } /* terminate */