From 820687a7b98a5031207893ff265f97c0a0ad403e Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 25 Apr 2017 15:12:56 -0700 Subject: rcuperf: Add writer_holdoff boot parameter This commit adds a writer_holdoff boot parameter to rcuperf, which is intended to be used to test Tree SRCU's auto-expediting. This boot parameter is in microseconds, and defaults to zero (that is, disabled). Set it to a bit larger than srcutree.exp_holdoff, keeping the nanosecond/microsecond conversion, to force Tree SRCU to auto-expedite more aggressively. This commit also adds documentation for this parameter, and fixes some alphabetization while in the neighborhood. Signed-off-by: Paul E. McKenney --- kernel/rcu/rcuperf.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel/rcu') diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c index 49c8ed6bd2fd..d80f11d9f8bd 100644 --- a/kernel/rcu/rcuperf.c +++ b/kernel/rcu/rcuperf.c @@ -68,6 +68,7 @@ torture_param(int, nwriters, -1, "Number of RCU updater threads"); torture_param(bool, shutdown, !IS_ENABLED(MODULE), "Shutdown at end of performance tests."); torture_param(bool, verbose, true, "Enable verbose debugging printk()s"); +torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable"); static char *perf_type = "rcu"; module_param(perf_type, charp, 0444); @@ -447,6 +448,8 @@ rcu_perf_writer(void *arg) } do { + if (writer_holdoff) + udelay(writer_holdoff); wdp = &wdpp[i]; *wdp = ktime_get_mono_fast_ns(); if (gp_async) { -- cgit v1.2.3-58-ga151