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| author |   Paul E. McKenney <paulmck@kernel.org> | 2023-05-16 07:02:01 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2023-07-14 15:01:48 -0700 |
| commit | 2226f3dc05a988ce81308bfc3d125f5d0b0d592c (patch) | |
| tree | c6a7155b6f33cf27b7d344f85ec233e4ab55f546 | |
| parent | Linux 6.5-rc1 (diff) | |
| download | wireguard-linux-2226f3dc05a988ce81308bfc3d125f5d0b0d592c.tar.xz wireguard-linux-2226f3dc05a988ce81308bfc3d125f5d0b0d592c.zip | |
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 <paulmck@kernel.org>
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 5 | ||||
| -rw-r--r-- | kernel/rcu/rcuscale.c | 4 |
2 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a1457995fd41..5ba231b786f8 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4983,6 +4983,11 @@ in microseconds. The default of zero says no holdoff. + rcuscale.writer_holdoff_jiffies= [KNL] + Additional write-side holdoff between grace + periods, but in jiffies. The default of zero + says no holdoff. + rcutorture.fqs_duration= [KNL] Set duration of force_quiescent_state bursts in microseconds. 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) { |