From bdea9e347783c2724997db7c5d5b45a301e2dc90 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 1 Jan 2016 13:47:19 -0800 Subject: rcutorture: Documentation for rcuperf kernel parameters This commit adds documentation for the new rcuperf module's kernel boot parameters. Signed-off-by: Paul E. McKenney --- Documentation/kernel-parameters.txt | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'Documentation/kernel-parameters.txt') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index ecc74fa4bfde..951af481da5a 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3284,6 +3284,38 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Lazy RCU callbacks are those which RCU can prove do nothing more than free memory. + rcuperf.gp_exp= [KNL] + Measure performance of expedited synchronous + grace-period primitives. + + rcuperf.nreaders= [KNL] + Set number of RCU readers. The value -1 selects + N, where N is the number of CPUs. A value + "n" less than -1 selects N-n+1, where N is again + the number of CPUs. For example, -2 selects N + (the number of CPUs), -3 selects N+1, and so on. + A value of "n" less than or equal to -N selects + a single reader. + + rcuperf.nwriters= [KNL] + Set number of RCU writers. The values operate + the same as for rcuperf.nreaders. + N, where N is the number of CPUs + + rcuperf.perf_runnable= [BOOT] + Start rcuperf running at boot time. + + rcuperf.shutdown= [KNL] + Shut the system down after performance tests + complete. This is useful for hands-off automated + testing. + + rcuperf.perf_type= [KNL] + Specify the RCU implementation to test. + + rcuperf.verbose= [KNL] + Enable additional printk() statements. + rcutorture.cbflood_inter_holdoff= [KNL] Set holdoff time (jiffies) between successive callback-flood tests. -- cgit v1.2.3 From df37e66bfdbb57e8cae7dbf39a0c66b1b8701338 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sat, 30 Jan 2016 20:56:38 -0800 Subject: rcutorture: Add rcuperf holdoff boot parameter to reduce interference Boot-time activity can legitimately grab CPUs for extended time periods, so the commit adds a boot parameter to delay the start of the performance test until boot has completed. Defaults to 10 seconds. Signed-off-by: Paul E. McKenney --- Documentation/kernel-parameters.txt | 6 ++++++ kernel/rcu/rcuperf.c | 5 +++++ 2 files changed, 11 insertions(+) (limited to 'Documentation/kernel-parameters.txt') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 951af481da5a..da9ee466789b 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3288,6 +3288,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Measure performance of expedited synchronous grace-period primitives. + rcuperf.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. + rcuperf.nreaders= [KNL] Set number of RCU readers. The value -1 selects N, where N is the number of CPUs. A value diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c index 12561f96f0a2..278600143bb6 100644 --- a/kernel/rcu/rcuperf.c +++ b/kernel/rcu/rcuperf.c @@ -59,6 +59,7 @@ MODULE_AUTHOR("Paul E. McKenney "); do { if (verbose) pr_alert("%s" PERF_FLAG "!!! %s\n", perf_type, s); } while (0) torture_param(bool, gp_exp, true, "Use expedited GP wait primitives"); +torture_param(int, holdoff, 10, "Holdoff time before test start (s)"); torture_param(int, nreaders, -1, "Number of RCU reader threads"); torture_param(int, nwriters, -1, "Number of RCU updater threads"); torture_param(bool, shutdown, false, "Shutdown at end of performance tests."); @@ -368,6 +369,10 @@ rcu_perf_writer(void *arg) set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)); sp.sched_priority = 1; sched_setscheduler_nocheck(current, SCHED_FIFO, &sp); + + if (holdoff) + schedule_timeout_uninterruptible(holdoff * HZ); + t = ktime_get_mono_fast_ns(); if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) { t_rcu_perf_writer_started = t; -- cgit v1.2.3