From 2226f3dc05a988ce81308bfc3d125f5d0b0d592c Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 16 May 2023 07:02:01 -0700 Subject: rcuscale: Permit blocking delays between writers Some workloads do isolated RCU work, and this can affect operation latencies. This commit therefore adds a writer_holdoff_jiffies module parameter that causes writers to block for the specified number of jiffies between each pair of consecutive write-side operations. Signed-off-by: Paul E. McKenney --- kernel/rcu/rcuscale.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/rcu') diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c index d1221731c7cf..4277037e0996 100644 --- a/kernel/rcu/rcuscale.c +++ b/kernel/rcu/rcuscale.c @@ -93,6 +93,7 @@ torture_param(bool, shutdown, RCUSCALE_SHUTDOWN, "Shutdown at end of scalability tests."); torture_param(int, verbose, 1, "Enable verbose debugging printk()s"); torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable"); +torture_param(int, writer_holdoff_jiffies, 0, "Holdoff (jiffies) between GPs, zero to disable"); torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?"); torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate."); torture_param(int, kfree_by_call_rcu, 0, "Use call_rcu() to emulate kfree_rcu()?"); @@ -414,6 +415,7 @@ rcu_scale_writer(void *arg) struct rcu_head *rhp = NULL; bool started = false, done = false, alldone = false; u64 t; + DEFINE_TORTURE_RANDOM(tr); u64 *wdp; u64 *wdpp = writer_durations[me]; @@ -448,6 +450,8 @@ rcu_scale_writer(void *arg) do { if (writer_holdoff) udelay(writer_holdoff); + if (writer_holdoff_jiffies) + schedule_timeout_idle(torture_random(&tr) % writer_holdoff_jiffies + 1); wdp = &wdpp[i]; *wdp = ktime_get_mono_fast_ns(); if (gp_async) { -- cgit v1.2.3