From 29d2090aef7b31df23ca846d365c6d21957486ba Mon Sep 17 00:00:00 2001
From: Mohammed Naser <mnaser@vexxhost.com>
Date: Thu, 15 Feb 2018 22:22:24 -0500
Subject: [PATCH] Add throughput limits that scale per-GB

This allows new values in QoS specs:
 - read_bytes_sec_per_gb
 - write_bytes_sec_per_gb
 - total_bytes_sec_per_gb

The bytes value specifed in the QoS spec is multiplied
by the size of the volume in initialize_connection,
and the result is passed along like a standard <x>_bytes_sec
QoS value.

Change-Id: Iafc22d37c4c50515d9f6cf1144ea25847c90f75d
---
 cinder/tests/unit/volume/test_connection.py   | 10 ++++++--
 cinder/volume/manager.py                      | 24 ++++++++-----------
 .../capacity-based-qos-9f5d174658a40bd5.yaml  | 13 ++++++++++
 3 files changed, 31 insertions(+), 16 deletions(-)
 create mode 100644 releasenotes/notes/capacity-based-qos-9f5d174658a40bd5.yaml

diff --git a/cinder/tests/unit/volume/test_connection.py b/cinder/tests/unit/volume/test_connection.py
index 25f6cb41f0d..9b75fea1d26 100644
--- a/cinder/tests/unit/volume/test_connection.py
+++ b/cinder/tests/unit/volume/test_connection.py
@@ -194,7 +194,10 @@ class VolumeConnectionTestCase(base.BaseVolumeTestCase):
                       'specs': {
                           'write_iops_sec_per_gb': 5,
                           'read_iops_sec_per_gb': 7700,
-                          'total_iops_sec_per_gb': 300000}
+                          'total_iops_sec_per_gb': 300000,
+                          'read_bytes_sec_per_gb': 10,
+                          'write_bytes_sec_per_gb': 40,
+                          'total_bytes_sec_per_gb': 1048576}
                       }
 
         with mock.patch.object(cinder.volume.volume_types,
@@ -206,7 +209,10 @@ class VolumeConnectionTestCase(base.BaseVolumeTestCase):
             mock_get_target.return_value = None
             qos_specs_expected = {'write_iops_sec': 15,
                                   'read_iops_sec': 23100,
-                                  'total_iops_sec': 900000}
+                                  'total_iops_sec': 900000,
+                                  'read_bytes_sec': 30,
+                                  'write_bytes_sec': 120,
+                                  'total_bytes_sec': 3145728}
             # initialize_connection() passes qos_specs that is designated to
             # be consumed by front-end or both front-end and back-end
             conn_info = self.volume.initialize_connection(
diff --git a/cinder/volume/manager.py b/cinder/volume/manager.py
index 765e5f0d7b9..ecf590e96d4 100644
--- a/cinder/volume/manager.py
+++ b/cinder/volume/manager.py
@@ -1602,22 +1602,18 @@ class VolumeManager(manager.CleanableManager,
             if qos and qos.get('consumer') in ['front-end', 'both']:
                 specs = qos.get('specs')
 
+            # NOTE(mnaser): The following configures for per-GB QoS
             if specs is not None:
-                # Compute fixed IOPS values for per-GB keys
-                if 'write_iops_sec_per_gb' in specs:
-                    specs['write_iops_sec'] = (
-                        int(specs['write_iops_sec_per_gb']) * int(volume.size))
-                    specs.pop('write_iops_sec_per_gb')
+                volume_size = int(volume.size)
+                tune_opts = ('read_iops_sec', 'read_bytes_sec',
+                             'write_iops_sec', 'write_bytes_sec',
+                             'total_iops_sec', 'total_bytes_sec')
 
-                if 'read_iops_sec_per_gb' in specs:
-                    specs['read_iops_sec'] = (
-                        int(specs['read_iops_sec_per_gb']) * int(volume.size))
-                    specs.pop('read_iops_sec_per_gb')
-
-                if 'total_iops_sec_per_gb' in specs:
-                    specs['total_iops_sec'] = (
-                        int(specs['total_iops_sec_per_gb']) * int(volume.size))
-                    specs.pop('total_iops_sec_per_gb')
+                for option in tune_opts:
+                    option_per_gb = '%s_per_gb' % option
+                    if option_per_gb in specs:
+                        specs[option] = int(specs[option_per_gb]) * volume_size
+                        specs.pop(option_per_gb)
 
         qos_spec = dict(qos_specs=specs)
         conn_info['data'].update(qos_spec)
diff --git a/releasenotes/notes/capacity-based-qos-9f5d174658a40bd5.yaml b/releasenotes/notes/capacity-based-qos-9f5d174658a40bd5.yaml
new file mode 100644
index 00000000000..e85112ceefe
--- /dev/null
+++ b/releasenotes/notes/capacity-based-qos-9f5d174658a40bd5.yaml
@@ -0,0 +1,13 @@
+---
+features:
+  - Cinder now allows for capacity based QoS which can be useful in
+    environments where storage performance scales with consumption (such as
+    RBD backed storage).  The newly added QoS specs are `read_iops_sec_per_gb`,
+    `write_iops_sec_per_gb`, `total_iops_sec_per_gb`, `read_bytes_sec_per_gb`,
+    `write_bytes_sec_per_gb` and `total_bytes_sec_per_gb`.  These values will
+    be multiplied by the size of the volume and passed to the consumer.
+
+    For example, setting `total_iops_sec_per_gb` to 30 and setting
+    `total_bytes_sec_per_gb` to `1048576` (1MB) then creating a 100 GB volume
+    with that QoS will result in a volume with 3,000 total IOPs and 100MB/s
+    throughput limit.