doc: Document rcuperf's module parameters

This commit adds documentation for the rcuperf module parameters.

Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index fb95fad81c79a065e728202a34a3dabac5653cb4..20cd00b78fc4125f100dceef28868b32db86062f 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4407,6 +4407,42 @@
                              reboot_cpu is s[mp]#### with #### being the processor
                                        to be used for rebooting.
 
+       refperf.holdoff= [KNL]
+                       Set test-start holdoff period.  The purpose of
+                       this parameter is to delay the start of the
+                       test until boot completes in order to avoid
+                       interference.
+
+       refperf.loops= [KNL]
+                       Set the number of loops over the synchronization
+                       primitive under test.  Increasing this number
+                       reduces noise due to loop start/end overhead,
+                       but the default has already reduced the per-pass
+                       noise to a handful of picoseconds on ca. 2020
+                       x86 laptops.
+
+       refperf.nreaders= [KNL]
+                       Set number of readers.  The default value of -1
+                       selects N, where N is roughly 75% of the number
+                       of CPUs.  A value of zero is an interesting choice.
+
+       refperf.nruns= [KNL]
+                       Set number of runs, each of which is dumped onto
+                       the console log.
+
+       refperf.readdelay= [KNL]
+                       Set the read-side critical-section duration,
+                       measured in microseconds.
+
+       refperf.shutdown= [KNL]
+                       Shut down the system at the end of the performance
+                       test.  This defaults to 1 (shut it down) when
+                       rcuperf is built into the kernel and to 0 (leave
+                       it running) when rcuperf is built as a module.
+
+       refperf.verbose= [KNL]
+                       Enable additional printk() statements.
+
        relax_domain_level=
                        [KNL, SMP] Set scheduler's default relax_domain_level.
                        See Documentation/admin-guide/cgroup-v1/cpusets.rst.