From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, rushikesh.s.kadam@intel.com,
urezki@gmail.com, neeraj.iitr10@gmail.com, frederic@kernel.org,
paulmck@kernel.org, rostedt@goodmis.org, vineeth@bitbyteword.org,
boqun.feng@gmail.com,
"Joel Fernandes (Google)" <joel@joelfernandes.org>
Subject: [PATCH v5 09/18] rcuscale: Add laziness and kfree tests
Date: Thu, 1 Sep 2022 22:17:11 +0000 [thread overview]
Message-ID: <20220901221720.1105021-10-joel@joelfernandes.org> (raw)
In-Reply-To: <20220901221720.1105021-1-joel@joelfernandes.org>
We aad 2 tests to rcuscale, first one is a startup test to check whether
we are not too lazy or too hard working. Two, emulate kfree_rcu() itself
to use call_rcu_lazy() and check memory pressure. In my testing,
call_rcu_lazy() does well to keep memory pressure under control, similar
to kfree_rcu().
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
kernel/rcu/rcuscale.c | 74 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 73 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index 3ef02d4a8108..6808f2e14385 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -95,6 +95,7 @@ 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, 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_rcu_by_lazy, 0, "Use call_rcu_lazy() to emulate kfree_rcu()?");
static char *scale_type = "rcu";
module_param(scale_type, charp, 0444);
@@ -659,6 +660,14 @@ struct kfree_obj {
struct rcu_head rh;
};
+/* Used if doing RCU-kfree'ing via call_rcu_lazy(). */
+static void kfree_rcu_lazy(struct rcu_head *rh)
+{
+ struct kfree_obj *obj = container_of(rh, struct kfree_obj, rh);
+
+ kfree(obj);
+}
+
static int
kfree_scale_thread(void *arg)
{
@@ -696,6 +705,11 @@ kfree_scale_thread(void *arg)
if (!alloc_ptr)
return -ENOMEM;
+ if (kfree_rcu_by_lazy) {
+ call_rcu_lazy(&(alloc_ptr->rh), kfree_rcu_lazy);
+ continue;
+ }
+
// By default kfree_rcu_test_single and kfree_rcu_test_double are
// initialized to false. If both have the same value (false or true)
// both are randomly tested, otherwise only the one with value true
@@ -738,6 +752,9 @@ kfree_scale_cleanup(void)
{
int i;
+ if (kfree_rcu_by_lazy)
+ rcu_force_call_rcu_to_lazy(false);
+
if (torture_cleanup_begin())
return;
@@ -767,11 +784,64 @@ kfree_scale_shutdown(void *arg)
return -EINVAL;
}
+// Used if doing RCU-kfree'ing via call_rcu_lazy().
+static unsigned long jiffies_at_lazy_cb;
+static struct rcu_head lazy_test1_rh;
+static int rcu_lazy_test1_cb_called;
+static void call_rcu_lazy_test1(struct rcu_head *rh)
+{
+ jiffies_at_lazy_cb = jiffies;
+ WRITE_ONCE(rcu_lazy_test1_cb_called, 1);
+}
+
static int __init
kfree_scale_init(void)
{
long i;
int firsterr = 0;
+ unsigned long orig_jif, jif_start;
+
+ // If lazy-rcu based kfree'ing is requested, then for kernels that
+ // support it, force all call_rcu() to call_rcu_lazy() so that non-lazy
+ // CBs do not remove laziness of the lazy ones (since the test tries to
+ // stress call_rcu_lazy() for OOM).
+ //
+ // Also, do a quick self-test to ensure laziness is as much as
+ // expected.
+ if (kfree_rcu_by_lazy && !IS_ENABLED(CONFIG_RCU_LAZY)) {
+ pr_alert("CONFIG_RCU_LAZY is disabled, falling back to kfree_rcu() "
+ "for delayed RCU kfree'ing\n");
+ kfree_rcu_by_lazy = 0;
+ }
+
+ if (kfree_rcu_by_lazy) {
+ /* do a test to check the timeout. */
+ orig_jif = rcu_lazy_get_jiffies_till_flush();
+
+ rcu_force_call_rcu_to_lazy(true);
+ rcu_lazy_set_jiffies_till_flush(2 * HZ);
+ rcu_barrier();
+
+ jif_start = jiffies;
+ jiffies_at_lazy_cb = 0;
+ call_rcu_lazy(&lazy_test1_rh, call_rcu_lazy_test1);
+
+ smp_cond_load_relaxed(&rcu_lazy_test1_cb_called, VAL == 1);
+
+ rcu_lazy_set_jiffies_till_flush(orig_jif);
+
+ if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) {
+ pr_alert("ERROR: Lazy CBs are not being lazy as expected!\n");
+ WARN_ON_ONCE(1);
+ return -1;
+ }
+
+ if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start > 3 * HZ)) {
+ pr_alert("ERROR: Lazy CBs are being too lazy!\n");
+ WARN_ON_ONCE(1);
+ return -1;
+ }
+ }
kfree_nrealthreads = compute_real(kfree_nthreads);
/* Start up the kthreads. */
@@ -784,7 +854,9 @@ kfree_scale_init(void)
schedule_timeout_uninterruptible(1);
}
- pr_alert("kfree object size=%zu\n", kfree_mult * sizeof(struct kfree_obj));
+ pr_alert("kfree object size=%zu, kfree_rcu_by_lazy=%d\n",
+ kfree_mult * sizeof(struct kfree_obj),
+ kfree_rcu_by_lazy);
kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
GFP_KERNEL);
--
2.37.2.789.g6183377224-goog
next prev parent reply other threads:[~2022-09-01 22:19 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-01 22:17 [PATCH v5 00/18] Implement call_rcu_lazy() and miscellaneous fixes Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 01/18] mm/slub: perform free consistency checks before call_rcu Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 02/18] mm/sl[au]b: rearrange struct slab fields to allow larger rcu_head Joel Fernandes (Google)
2022-09-02 9:26 ` Vlastimil Babka
2022-09-02 9:30 ` Vlastimil Babka
2022-09-02 15:09 ` Joel Fernandes
2022-09-03 13:53 ` Paul E. McKenney
2022-09-01 22:17 ` [PATCH v5 03/18] rcu/tree: Use READ_ONCE() for lockless read of rnp->qsmask Joel Fernandes (Google)
2022-09-06 22:26 ` Boqun Feng
2022-09-06 22:31 ` Joel Fernandes
2022-09-01 22:17 ` [PATCH v5 04/18] rcu: Fix late wakeup when flush of bypass cblist happens Joel Fernandes (Google)
2022-09-02 11:35 ` Frederic Weisbecker
2022-09-02 23:58 ` Joel Fernandes
2022-09-03 15:10 ` Paul E. McKenney
2022-09-04 21:13 ` Frederic Weisbecker
2022-09-03 14:04 ` Paul E. McKenney
2022-09-03 14:05 ` Joel Fernandes
2022-09-06 3:07 ` Joel Fernandes
2022-09-06 9:48 ` Frederic Weisbecker
2022-09-07 2:43 ` Joel Fernandes
2022-09-01 22:17 ` [PATCH v5 05/18] rcu: Move trace_rcu_callback() before bypassing Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 06/18] rcu: Introduce call_rcu_lazy() API implementation Joel Fernandes (Google)
2022-09-02 15:21 ` Frederic Weisbecker
2022-09-02 23:09 ` Joel Fernandes
2022-09-05 12:59 ` Frederic Weisbecker
2022-09-05 20:18 ` Joel Fernandes
2022-09-05 20:32 ` Joel Fernandes
2022-09-06 8:55 ` Paul E. McKenney
2022-09-06 16:16 ` Joel Fernandes
2022-09-06 17:05 ` Paul E. McKenney
2022-09-03 22:00 ` Joel Fernandes
2022-09-04 21:01 ` Frederic Weisbecker
2022-09-05 20:20 ` Joel Fernandes
2022-09-06 3:05 ` Joel Fernandes
2022-09-06 15:17 ` Frederic Weisbecker
2022-09-06 16:15 ` Joel Fernandes
2022-09-06 16:31 ` Joel Fernandes
2022-09-06 16:38 ` Joel Fernandes
2022-09-06 16:43 ` Joel Fernandes
2022-09-06 19:11 ` Frederic Weisbecker
2022-09-07 2:56 ` Joel Fernandes
2022-09-07 9:56 ` Frederic Weisbecker
2022-09-07 10:03 ` Frederic Weisbecker
2022-09-07 14:01 ` Joel Fernandes
2022-09-07 0:06 ` Joel Fernandes
2022-09-07 9:40 ` Frederic Weisbecker
2022-09-07 13:44 ` Joel Fernandes
2022-09-07 15:38 ` Frederic Weisbecker
2022-09-07 15:39 ` Joel Fernandes
2022-09-21 23:52 ` Joel Fernandes
2022-09-06 18:16 ` Uladzislau Rezki
2022-09-06 18:21 ` Joel Fernandes
2022-09-07 8:52 ` Uladzislau Rezki
2022-09-07 15:23 ` Joel Fernandes
2022-09-03 14:03 ` Paul E. McKenney
2022-09-03 14:05 ` Joel Fernandes
2022-09-01 22:17 ` [PATCH v5 07/18] rcu: shrinker for lazy rcu Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 08/18] rcu: Add per-CB tracing for queuing, flush and invocation Joel Fernandes (Google)
2022-09-02 16:48 ` kernel test robot
2022-09-03 12:39 ` Paul E. McKenney
2022-09-03 14:07 ` Joel Fernandes
2022-09-02 19:01 ` kernel test robot
2022-09-01 22:17 ` Joel Fernandes (Google) [this message]
2022-09-01 22:17 ` [PATCH v5 10/18] rcutorture: Add test code for call_rcu_lazy() Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 11/18] fs: Move call_rcu() to call_rcu_lazy() in some paths Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 12/18] cred: Move call_rcu() to call_rcu_lazy() Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 13/18] security: " Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 14/18] net/core: " Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 15/18] kernel: Move various core kernel usages " Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 16/18] lib: Move call_rcu() " Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 17/18] i915: " Joel Fernandes (Google)
2022-09-01 22:17 ` [PATCH v5 18/18] fork: Move thread_stack_free_rcu() " Joel Fernandes (Google)
2022-09-03 15:22 ` [PATCH v5 00/18] Implement call_rcu_lazy() and miscellaneous fixes Paul E. McKenney
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