Experiment: nreaders=1 nwriters=1 reader_cpu_offset=0 writer_cpu_offset=0
Average grace-period duration: 108376 microseconds
Minimum grace-period duration: 13000.4
50th percentile grace-period duration: 115000
90th percentile grace-period duration: 121000
99th percentile grace-period duration: 121004
Maximum grace-period duration: 219000
Grace periods: 101 Batches: 1 Ratio: 101
Experiment: nreaders=1 nwriters=1 reader_cpu_offset=0 writer_cpu_offset=1
Average grace-period duration: 185950 microseconds
Minimum grace-period duration: 8999.84
50th percentile grace-period duration: 217946
90th percentile grace-period duration: 218003
99th percentile grace-period duration: 218018
Maximum grace-period duration: 272195
Grace periods: 101 Batches: 1 Ratio: 101
Signed-off-by: Yuzhuo Jing <yuzhuo@xxxxxxxxxx>
---
.../admin-guide/kernel-parameters.txt | 19 +++++++++++++++++++
kernel/rcu/rcuscale.c | 16 +++++++++++-----
2 files changed, 30 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 5e233e511f81..f68651c103a4 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1,3 +1,4 @@
+# vim: noet:sw=8:sts=8:
accept_memory= [MM]
Format: { eager | lazy }
default: lazy
@@ -5513,6 +5514,12 @@
test until boot completes in order to avoid
interference.
+ rcuscale.kfree_cpu_offset= [KNL]
+ Set the starting CPU affinity index of kfree threads.
+ CPU affinity is assigned sequentially from
+ kfree_cpu_offset to kfree_cpu_offset+kfree_nthreads,
+ modded by number of CPUs. Negative value is reset to 0.
+
rcuscale.kfree_by_call_rcu= [KNL]
In kernels built with CONFIG_RCU_LAZY=y, test
call_rcu() instead of kfree_rcu().
@@ -5567,6 +5574,12 @@
the same as for rcuscale.nreaders.
N, where N is the number of CPUs
+ rcuscale.reader_cpu_offset= [KNL]
+ Set the starting CPU affinity index of reader threads.
+ CPU affinity is assigned sequentially from
+ reader_cpu_offset to reader_cpu_offset+nreaders, modded
+ by number of CPUs. Negative value is reset to 0.
+
rcuscale.scale_type= [KNL]
Specify the RCU implementation to test.
@@ -5578,6 +5591,12 @@
rcuscale.verbose= [KNL]
Enable additional printk() statements.
+ rcuscale.writer_cpu_offset= [KNL]
+ Set the starting CPU affinity index of writer threads.
+ CPU affinity is assigned sequentially from
+ writer_cpu_offset to writer_cpu_offset+nwriters, modded
+ by number of CPUs. Negative value is reset to 0.
+
rcuscale.writer_holdoff= [KNL]
Write-side holdoff between grace periods,
in microseconds. The default of zero says
diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index 43bcaeac457f..1208169be15e 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -95,12 +95,15 @@ torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
torture_param(int, minruntime, 0, "Minimum run time (s)");
torture_param(int, nreaders, -1, "Number of RCU reader threads");
torture_param(int, nwriters, -1, "Number of RCU updater threads");
+torture_param(int, reader_cpu_offset, 0, "Offset of reader CPU affinity")
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_cpu_offset, 0, "Offset of writer CPU affinity")
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(bool, writer_no_print, false, "Do not print writer durations to ring buffer");
+torture_param(int, kfree_cpu_offset, 0, "Offset of kfree CPU affinity")
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()?");
@@ -495,7 +498,7 @@ rcu_scale_reader(void *arg)
long me = (long)arg;
VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
- set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
+ set_cpus_allowed_ptr(current, cpumask_of((reader_cpu_offset + me) % nr_cpu_ids));
set_user_nice(current, MAX_NICE);
atomic_inc(&n_rcu_scale_reader_started);
@@ -585,7 +588,7 @@ rcu_scale_writer(void *arg)
VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
WARN_ON(!wdpp);
- set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
+ set_cpus_allowed_ptr(current, cpumask_of((writer_cpu_offset + me) % nr_cpu_ids));
current->flags |= PF_NO_SETAFFINITY;
sched_set_fifo_low(current);
@@ -719,8 +722,8 @@ static void
rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
{
pr_alert("%s" SCALE_FLAG
- "--- %s: gp_async=%d gp_async_max=%d gp_exp=%d holdoff=%d minruntime=%d nreaders=%d nwriters=%d writer_holdoff=%d writer_holdoff_jiffies=%d verbose=%d shutdown=%d\n",
- scale_type, tag, gp_async, gp_async_max, gp_exp, holdoff, minruntime, nrealreaders, nrealwriters, writer_holdoff, writer_holdoff_jiffies, verbose, shutdown);
+ "--- %s: gp_async=%d gp_async_max=%d gp_exp=%d holdoff=%d minruntime=%d nreaders=%d nwriters=%d reader_cpu_offset=%d writer_cpu_offset=%d writer_holdoff=%d writer_holdoff_jiffies=%d kfree_cpu_offset=%d verbose=%d shutdown=%d\n",
+ scale_type, tag, gp_async, gp_async_max, gp_exp, holdoff, minruntime, nrealreaders, nrealwriters, reader_cpu_offset, writer_cpu_offset, writer_holdoff, writer_holdoff_jiffies, kfree_cpu_offset, verbose, shutdown);
}
/*
@@ -785,7 +788,7 @@ kfree_scale_thread(void *arg)
DEFINE_TORTURE_RANDOM(tr);
VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started");
- set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
+ set_cpus_allowed_ptr(current, cpumask_of((kfree_cpu_offset + me) % nr_cpu_ids));
set_user_nice(current, MAX_NICE);
kfree_rcu_test_both = (kfree_rcu_test_single == kfree_rcu_test_double);
@@ -1446,6 +1449,9 @@ rcu_scale_init(void)
atomic_set(&n_rcu_scale_reader_started, 0);
atomic_set(&n_rcu_scale_writer_started, 0);
atomic_set(&n_rcu_scale_writer_finished, 0);
+ reader_cpu_offset = max(reader_cpu_offset, 0);
+ writer_cpu_offset = max(writer_cpu_offset, 0);
+ kfree_cpu_offset = max(kfree_cpu_offset, 0);
rcu_scale_print_module_parms(cur_ops, "Start of test");
if (!block_start)
--
2.50.1.552.g942d659e1b-goog
