github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-23 14:42:08 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

rcuscale: Permit blocking delays between writers

Browse Source 
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>
This commit is contained in:
Paul E. McKenney 2023-05-16 07:02:01 -07:00
parent 06c2afb862
commit 2226f3dc05
2 changed files with 9 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
Documentation/admin-guide/kernel-parameters.txt
View File

@ -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.

4
kernel/rcu/rcuscale.c
View File

@ -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) {