From: Lennart Poettering <lennart@poettering.net>
Date: Sat, 11 Jul 2015 17:18:35 +0000 (-0300)
Subject: README: document that RT group sched should be turned off
X-Git-Tag: v223~117^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=f4e74be1856b3ac058acbf1be321c31d5299f69f;p=thirdparty%2Fsystemd.git

README: document that RT group sched should be turned off

https://bugs.freedesktop.org/show_bug.cgi?id=87570
https://bugzilla.redhat.com/show_bug.cgi?id=1229700
---

diff --git a/README b/README
index 53220ff3f21..e15fa77deee 100644
--- a/README
+++ b/README
@@ -82,11 +82,11 @@ REQUIREMENTS:
           CONFIG_SECCOMP
           CONFIG_CHECKPOINT_RESTORE (for the kcmp() syscall)
 
-        Required for CPUShares in resource control unit settings
+        Required for CPUShares= in resource control unit settings
           CONFIG_CGROUP_SCHED
           CONFIG_FAIR_GROUP_SCHED
 
-        Required for CPUQuota in resource control unit settings
+        Required for CPUQuota= in resource control unit settings
           CONFIG_CFS_BANDWIDTH
 
         For systemd-bootchart, several proc debug interfaces are required:
@@ -97,6 +97,15 @@ REQUIREMENTS:
           CONFIG_EFIVAR_FS
           CONFIG_EFI_PARTITION
 
+        We recommend to turn off Real-Time group scheduling in the
+        kernel when using systemd. RT group scheduling effectively
+        makes RT scheduling unavailable for most userspace, since it
+        requires explicit assignment of RT budgets to each unit whose
+        processes making use of RT. As there's no sensible way to
+        assign these budgets automatically this cannot really be
+        fixed, and it's best to disable group scheduling hence.
+           CONFIG_RT_GROUP_SCHED=n
+
         Note that kernel auditing is broken when used with systemd's
         container code. When using systemd in conjunction with
         containers, please make sure to either turn off auditing at