system: move performance tuning into options chapter

1 files changed, 38 insertions, 2 deletions

diff --git a/docs/system/options.rst b/docs/system/options.rst
index 82ad4801..68f715c0 100644
--- a/docs/system/options.rst
+++ b/docs/system/options.rst
@@ -6,8 +6,9 @@ Options
 
 This chapter describe the possibilities of advanced system behavior.
 
+*******
 General
-#######
+*******
 
 .. cfgcmd:: set system options beep-if-fully-booted
 
@@ -21,8 +22,9 @@ General
 
    Automatically teboot system on kernel panic after 60 seconds.
 
+***********
 HTTP client
-###########
+***********
 
 .. cfgcmd:: set system options http-client source-address <address>
 
@@ -37,3 +39,37 @@ HTTP client
 .. note:: `source-address` and `source-interface` can not be used at the same time.
 
 
+***********
+Performance
+***********
+
+As more and more routers run on Hypervisors, expecially with a :abbr:`NOS
+(Network Operating System)` as VyOS, it makes fewer and fewer sense to use
+static resource bindings like ``smp-affinity`` as present in VyOS 1.2 and
+earlier to pin certain interrupt handlers to specific CPUs.
+
+We now utilize `tuned` for dynamic resource balancing based on profiles.
+
+  .. seealso:: https://access.redhat.com/sites/default/files/attachments/201501-perf-brief-low-latency-tuning-rhel7-v2.1.pdf
+
+.. cfgcmd:: set system options performance < throughput | latency >
+
+  Configure one of the predefined system performance profiles.
+
+  * ``throughput``: A server profile focused on improving network throughput.
+    This profile favors performance over power savings by setting ``intel_pstate``
+    and ``max_perf_pct=100`` and increasing kernel network buffer sizes.
+
+    It enables transparent huge pages, and uses cpupower to set the performance
+    cpufreq governor. It also sets ``kernel.sched_min_granularity_ns`` to 10 us,
+    ``kernel.sched_wakeup_granularity_ns`` to 15 uss, and ``vm.dirty_ratio`` to
+    40%.
+
+  * ``latency``: A server profile focused on lowering network latency.
+    This profile favors performance over power savings by setting ``intel_pstate``
+    and ``min_perf_pct=100``.
+
+    It disables transparent huge pages, and automatic NUMA balancing. It also
+    uses cpupower to set the performance cpufreq governor, and requests a
+    cpu_dma_latency value of 1. It also sets busy_read and busy_poll times to
+    50 us, and tcp_fastopen to 3.