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From:   Tejun Heo <tj@kernel.org>
To:     axboe@kernel.dk
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel-team@fb.com, cgroups@vger.kernel.org, newella@fb.com,
        josef@toxicpanda.com, asml.silence@gmail.com, ming.lei@redhat.com,
        bvanassche@acm.org, Tejun Heo <tj@kernel.org>
Subject: [PATCH 3/4] iocost_monitor: exit successfully if interval is zero
Date:   Mon, 13 Apr 2020 12:27:57 -0400
Message-Id: <20200413162758.97252-4-tj@kernel.org>
In-Reply-To: <20200413162758.97252-1-tj@kernel.org>
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This is to help external tools to decide whether iocost_monitor has all its
requirements met or not based on the exit status of an -i0 run.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 tools/cgroup/iocost_monitor.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/cgroup/iocost_monitor.py b/tools/cgroup/iocost_monitor.py
index 7427a5ee761b..eb2363b868c5 100644
--- a/tools/cgroup/iocost_monitor.py
+++ b/tools/cgroup/iocost_monitor.py
@@ -28,7 +28,8 @@ parser.add_argument('devname', metavar='DEV',
 parser.add_argument('--cgroup', action='append', metavar='REGEX',
                     help='Regex for target cgroups, ')
 parser.add_argument('--interval', '-i', metavar='SECONDS', type=float, default=1,
-                    help='Monitoring interval in seconds')
+                    help='Monitoring interval in seconds (0 exits immediately '
+                    'after checking requirements)')
 parser.add_argument('--json', action='store_true',
                     help='Output in json')
 args = parser.parse_args()
@@ -243,6 +244,9 @@ ioc = None
 if ioc is None:
     err(f'Could not find ioc for {devname}');
 
+if interval == 0:
+    sys.exit(0)
+
 # Keep printing
 while True:
     now = time.time()
-- 
2.25.2