[Xen-changelog] [xen staging] docs: add "sched-gran" boot parameter documentation

[patchbot@xxxxxxx]

commit b8ab1edad7d6999b8f926bade3904d5e857b4862
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Wed Oct 2 09:27:45 2019 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Oct 4 13:04:28 2019 +0200

    docs: add "sched-gran" boot parameter documentation
    
    Add documentation for the new "sched-gran" hypervisor boot parameter.
    
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 docs/misc/xen-command-line.pandoc | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/docs/misc/xen-command-line.pandoc 
b/docs/misc/xen-command-line.pandoc
index f5410b37d9..67df80c50d 100644
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -1782,6 +1782,34 @@ Set the timeslice of the credit1 scheduler, in 
milliseconds.  The
 default is 30ms.  Reasonable values may include 10, 5, or even 1 for
 very latency-sensitive workloads.
 
+### sched-gran (x86)
+> `= cpu | core | socket`
+
+> Default: `sched-gran=cpu`
+
+Set the scheduling granularity. In case the granularity is larger than 1 (e.g.
+`core`on a SMT-enabled system, or `socket`) multiple vcpus are assigned
+statically to a "scheduling unit" which will then be subject to scheduling.
+This assignment of vcpus to scheduling units is fixed.
+
+`cpu`: Vcpus will be scheduled individually on single cpus (e.g. a
+hyperthread using x86/Intel terminology)
+
+`core`: As many vcpus as there are cpus on a physical core are scheduled
+together on a physical core.
+
+`socket`: As many vcpus as there are cpus on a physical sockets are scheduled
+together on a physical socket.
+
+Note: a value other than `cpu` will result in rejecting a runtime modification
+attempt of the "smt" setting.
+
+Note: for AMD x86 processors before Fam17 the terminology in the official data
+sheets is different: a cpu is named "core" and multiple "cores" are running
+in the same "compute unit". As from Fam17 on AMD is using the same names as
+Intel ("thread" and "core") the topology levels are named "cpu", "core" and
+"socket" even on older AMD processors.
+
 ### sched_ratelimit_us
 > `= <integer>`
 
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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