cgroup: rework startup logic

Introduce a (unsigned long) -1 as "unset" state for cpu shares/block io
weights, and keep the startup unit set around all the time.

1 files changed, 27 insertions, 38 deletions

diff --git a/man/systemd.resource-control.xml b/man/systemd.resource-control.xml
index 33d2f2e102..a1f63dd66b 100644
--- a/man/systemd.resource-control.xml
+++ b/man/systemd.resource-control.xml
@@ -115,6 +115,7 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>.
 
       <varlistentry>
         <term><varname>CPUShares=<replaceable>weight</replaceable></varname></term>
+        <term><varname>StartupCPUShares=<replaceable>weight</replaceable></varname></term>
 
         <listitem>
           <para>Assign the specified CPU time share weight to the
@@ -122,10 +123,17 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>.
           the <literal>cpu.shares</literal> control group attribute,
           which defaults to 1024. For details about this control group
           attribute, see <ulink
-          url="https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt">sched-design-CFS.txt</ulink>
-          The available CPU time is split up among all units within a
+          url="https://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt">sched-design-CFS.txt</ulink>.
+          The available CPU time is split up among all units within one
           slice relative to their CPU time share weight.</para>
 
+          <para>While <varname>StartupCPUShares=</varname> only
+          applies to the startup phase of the system,
+          <varname>CPUShares=</varname> applies to the later runtime
+          of the system, and if the former is not set also to the
+          startup phase. This allows priorizing specific services at
+          boot-up differently than during runtime.</para>
+
           <para>Implies <literal>CPUAccounting=true</literal>.</para>
         </listitem>
       </varlistentry>
@@ -171,18 +179,6 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>.
       </varlistentry>
 
       <varlistentry>
-        <term><varname>StartupCPUShares=<replaceable>weight</replaceable></varname></term>
-
-        <listitem>
-          <para>Similar to <varname>CPUShares=</varname>. However,
-          only be assigned on startup state. After finishing startup, will be
-          re-assigned by <varname>CPUShares=</varname>. If
-          <varname>CPUShares=</varname> is not specified, then it will be
-          assigned to default(1024).</para>
-        </listitem>
-      </varlistentry>
-
-      <varlistentry>
         <term><varname>MemoryAccounting=</varname></term>
 
         <listitem>
@@ -233,19 +229,24 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>.
 
       <varlistentry>
         <term><varname>BlockIOWeight=<replaceable>weight</replaceable></varname></term>
+        <term><varname>StartupBlockIOWeight=<replaceable>weight</replaceable></varname></term>
 
-        <listitem><para>Set the default
-        overall block IO weight for the
-        executed processes. Takes a single
-        weight value (between 10 and 1000) to
-        set the default block IO weight. This
-        controls the
-        <literal>blkio.weight</literal>
-        control group attribute, which
-        defaults to 1000. For details about
-        this control group attribute, see
-        <ulink
-            url="https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.</para>
+        <listitem><para>Set the default overall block IO weight for
+        the executed processes. Takes a single weight value (between
+        10 and 1000) to set the default block IO weight. This controls
+        the <literal>blkio.weight</literal> control group attribute,
+        which defaults to 1000. For details about this control group
+        attribute, see <ulink
+        url="https://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.
+        The available IO bandwidth is split up among all units within
+        one slice relative to their block IO weight.</para>
+
+        <para>While <varname>StartupBlockIOWeight=</varname> only
+        applies to the startup phase of the system,
+        <varname>BlockIOWeight=</varname> applies to the later runtime
+        of the system, and if the former is not set also to the
+        startup phase. This allows priorizing specific services at
+        boot-up differently than during runtime.</para>
 
         <para>Implies
         <literal>BlockIOAccounting=true</literal>.</para>
@@ -253,18 +254,6 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>.
       </varlistentry>
 
       <varlistentry>
-        <term><varname>StartupBlockIOWeight=<replaceable>weight</replaceable></varname></term>
-
-        <listitem>
-          <para>Similar to <varname>BlockIOWeight=</varname>. However,
-          only be assigned on startup state. After finishing startup, will be
-          re-assigned by <varname>BlockIOWeight=</varname>. If
-          <varname>BlockIOWeight=</varname> is not specified, then it will be
-          assigned to default(1000).</para>
-        </listitem>
-      </varlistentry>
-
-      <varlistentry>
         <term><varname>BlockIODeviceWeight=<replaceable>device</replaceable> <replaceable>weight</replaceable></varname></term>
 
         <listitem>