This allows us to increase memory pressure dynamically using a new
rcuperf boot command line parameter called 'rcumult'.
Signed-off-by: Joel Fernandes (Google) <[email protected]>
---
The Series v1->v2 only has added a new patch (3/3).
kernel/rcu/rcuperf.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index a4a8d097d84d9..16dd1e6b7c09f 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -88,6 +88,7 @@ torture_param(bool, shutdown, RCUPERF_SHUTDOWN,
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() perf test?");
+torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
static char *perf_type = "rcu";
module_param(perf_type, charp, 0444);
@@ -635,7 +636,7 @@ kfree_perf_thread(void *arg)
}
for (i = 0; i < kfree_alloc_num; i++) {
- alloc_ptr = kmalloc(sizeof(struct kfree_obj), GFP_KERNEL);
+ alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
if (!alloc_ptr)
return -ENOMEM;
@@ -722,6 +723,8 @@ kfree_perf_init(void)
schedule_timeout_uninterruptible(1);
}
+ pr_alert("kfree object size=%lu\n", kfree_mult * sizeof(struct kfree_obj));
+
kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
GFP_KERNEL);
if (kfree_reader_tasks == NULL) {
--
2.25.1.481.gfbce0eb801-goog
We can relax the correctness of counting of number of queued objects in
favor of not hurting performance, by locklessly sampling per-cpu
counters. This should be Ok since under high memory pressure, it should not
matter if we are off by a few objects while counting. The shrinker will
still do the reclaim.
Signed-off-by: Joel Fernandes (Google) <[email protected]>
---
kernel/rcu/tree.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index dc570dff68d7b..875e7162ddcce 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2916,7 +2916,7 @@ static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp)
krcp->head = NULL;
}
- krcp->count = 0;
+ WRITE_ONCE(krcp->count, 0);
/*
* One work is per one batch, so there are two "free channels",
@@ -3054,7 +3054,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
krcp->head = head;
}
- krcp->count++;
+ WRITE_ONCE(krcp->count, krcp->count + 1);
// Set timer to drain after KFREE_DRAIN_JIFFIES.
if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING &&
@@ -3080,9 +3080,7 @@ kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
for_each_online_cpu(cpu) {
struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
- spin_lock_irqsave(&krcp->lock, flags);
- count += krcp->count;
- spin_unlock_irqrestore(&krcp->lock, flags);
+ count += READ_ONCE(krcp->count);
}
return count;
--
2.25.1.481.gfbce0eb801-goog
On Mon, Mar 16, 2020 at 12:32:26PM -0400, Joel Fernandes (Google) wrote:
> This allows us to increase memory pressure dynamically using a new
> rcuperf boot command line parameter called 'rcumult'.
>
> Signed-off-by: Joel Fernandes (Google) <[email protected]>
Applied for testing and review, thank you!
Thanx, Paul
> ---
>
> The Series v1->v2 only has added a new patch (3/3).
>
>
> kernel/rcu/rcuperf.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
> index a4a8d097d84d9..16dd1e6b7c09f 100644
> --- a/kernel/rcu/rcuperf.c
> +++ b/kernel/rcu/rcuperf.c
> @@ -88,6 +88,7 @@ torture_param(bool, shutdown, RCUPERF_SHUTDOWN,
> 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() perf test?");
> +torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
>
> static char *perf_type = "rcu";
> module_param(perf_type, charp, 0444);
> @@ -635,7 +636,7 @@ kfree_perf_thread(void *arg)
> }
>
> for (i = 0; i < kfree_alloc_num; i++) {
> - alloc_ptr = kmalloc(sizeof(struct kfree_obj), GFP_KERNEL);
> + alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
> if (!alloc_ptr)
> return -ENOMEM;
>
> @@ -722,6 +723,8 @@ kfree_perf_init(void)
> schedule_timeout_uninterruptible(1);
> }
>
> + pr_alert("kfree object size=%lu\n", kfree_mult * sizeof(struct kfree_obj));
> +
> kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
> GFP_KERNEL);
> if (kfree_reader_tasks == NULL) {
> --
> 2.25.1.481.gfbce0eb801-goog
On Tue, Mar 17, 2020 at 02:08:22PM -0700, Paul E. McKenney wrote:
> On Mon, Mar 16, 2020 at 12:32:26PM -0400, Joel Fernandes (Google) wrote:
> > This allows us to increase memory pressure dynamically using a new
> > rcuperf boot command line parameter called 'rcumult'.
> >
> > Signed-off-by: Joel Fernandes (Google) <[email protected]>
>
> Applied for testing and review, thank you!
But testing did not go far:
kernel/rcu/tree.c: In function ‘kfree_rcu_shrink_count’:
kernel/rcu/tree.c:3120:16: warning: unused variable ‘flags’ [-Wunused-variable]
unsigned long flags, count = 0;
^~~~~
I will drop these and await a replacement.
Thanx, Paul
> > ---
> >
> > The Series v1->v2 only has added a new patch (3/3).
> >
> >
> > kernel/rcu/rcuperf.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
> > index a4a8d097d84d9..16dd1e6b7c09f 100644
> > --- a/kernel/rcu/rcuperf.c
> > +++ b/kernel/rcu/rcuperf.c
> > @@ -88,6 +88,7 @@ torture_param(bool, shutdown, RCUPERF_SHUTDOWN,
> > 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() perf test?");
> > +torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
> >
> > static char *perf_type = "rcu";
> > module_param(perf_type, charp, 0444);
> > @@ -635,7 +636,7 @@ kfree_perf_thread(void *arg)
> > }
> >
> > for (i = 0; i < kfree_alloc_num; i++) {
> > - alloc_ptr = kmalloc(sizeof(struct kfree_obj), GFP_KERNEL);
> > + alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
> > if (!alloc_ptr)
> > return -ENOMEM;
> >
> > @@ -722,6 +723,8 @@ kfree_perf_init(void)
> > schedule_timeout_uninterruptible(1);
> > }
> >
> > + pr_alert("kfree object size=%lu\n", kfree_mult * sizeof(struct kfree_obj));
> > +
> > kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
> > GFP_KERNEL);
> > if (kfree_reader_tasks == NULL) {
> > --
> > 2.25.1.481.gfbce0eb801-goog
On Tue, Mar 17, 2020 at 5:45 PM Paul E. McKenney <[email protected]> wrote:
>
> On Tue, Mar 17, 2020 at 02:08:22PM -0700, Paul E. McKenney wrote:
> > On Mon, Mar 16, 2020 at 12:32:26PM -0400, Joel Fernandes (Google) wrote:
> > > This allows us to increase memory pressure dynamically using a new
> > > rcuperf boot command line parameter called 'rcumult'.
> > >
> > > Signed-off-by: Joel Fernandes (Google) <[email protected]>
> >
> > Applied for testing and review, thank you!
>
> But testing did not go far:
>
> kernel/rcu/tree.c: In function ‘kfree_rcu_shrink_count’:
> kernel/rcu/tree.c:3120:16: warning: unused variable ‘flags’ [-Wunused-variable]
> unsigned long flags, count = 0;
I fixed the warning already but did not resend since it was just the
one unused variable warning. The patches are otherwise good to apply.
Sorry, and I can resend it soon if you are not reapplying right now.
thanks,
- Joel
On Tue, Mar 17, 2020 at 06:30:51PM -0400, Joel Fernandes wrote:
> On Tue, Mar 17, 2020 at 5:45 PM Paul E. McKenney <[email protected]> wrote:
> >
> > On Tue, Mar 17, 2020 at 02:08:22PM -0700, Paul E. McKenney wrote:
> > > On Mon, Mar 16, 2020 at 12:32:26PM -0400, Joel Fernandes (Google) wrote:
> > > > This allows us to increase memory pressure dynamically using a new
> > > > rcuperf boot command line parameter called 'rcumult'.
> > > >
> > > > Signed-off-by: Joel Fernandes (Google) <[email protected]>
> > >
> > > Applied for testing and review, thank you!
> >
> > But testing did not go far:
> >
> > kernel/rcu/tree.c: In function ‘kfree_rcu_shrink_count’:
> > kernel/rcu/tree.c:3120:16: warning: unused variable ‘flags’ [-Wunused-variable]
> > unsigned long flags, count = 0;
>
> I fixed the warning already but did not resend since it was just the
> one unused variable warning. The patches are otherwise good to apply.
> Sorry, and I can resend it soon if you are not reapplying right now.
So remove "flags, " and all is well?
If so, I can just as easily fix that as take a new series. But next
time, please give a fella a warning. ;-)
Thanx, Paul
On March 17, 2020 6:48:20 PM EDT, "Paul E. McKenney" <[email protected]> wrote:
>On Tue, Mar 17, 2020 at 06:30:51PM -0400, Joel Fernandes wrote:
>> On Tue, Mar 17, 2020 at 5:45 PM Paul E. McKenney <[email protected]>
>wrote:
>> >
>> > On Tue, Mar 17, 2020 at 02:08:22PM -0700, Paul E. McKenney wrote:
>> > > On Mon, Mar 16, 2020 at 12:32:26PM -0400, Joel Fernandes (Google)
>wrote:
>> > > > This allows us to increase memory pressure dynamically using a
>new
>> > > > rcuperf boot command line parameter called 'rcumult'.
>> > > >
>> > > > Signed-off-by: Joel Fernandes (Google) <[email protected]>
>> > >
>> > > Applied for testing and review, thank you!
>> >
>> > But testing did not go far:
>> >
>> > kernel/rcu/tree.c: In function ‘kfree_rcu_shrink_count’:
>> > kernel/rcu/tree.c:3120:16: warning: unused variable ‘flags’
>[-Wunused-variable]
>> > unsigned long flags, count = 0;
>>
>> I fixed the warning already but did not resend since it was just the
>> one unused variable warning. The patches are otherwise good to apply.
>> Sorry, and I can resend it soon if you are not reapplying right now.
>
>So remove "flags, " and all is well?
Yes, that's right. I dropped the lock but forgot to remove it.
>If so, I can just as easily fix that as take a new series. But next
>time, please give a fella a warning. ;-)
Will do, my bad. Thank you ;-)
- Joel
>
> Thanx, Paul
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
On Tue, Mar 17, 2020 at 07:37:47PM -0400, [email protected] wrote:
>
>
> On March 17, 2020 6:48:20 PM EDT, "Paul E. McKenney" <[email protected]> wrote:
> >On Tue, Mar 17, 2020 at 06:30:51PM -0400, Joel Fernandes wrote:
> >> On Tue, Mar 17, 2020 at 5:45 PM Paul E. McKenney <[email protected]>
> >wrote:
> >> >
> >> > On Tue, Mar 17, 2020 at 02:08:22PM -0700, Paul E. McKenney wrote:
> >> > > On Mon, Mar 16, 2020 at 12:32:26PM -0400, Joel Fernandes (Google)
> >wrote:
> >> > > > This allows us to increase memory pressure dynamically using a
> >new
> >> > > > rcuperf boot command line parameter called 'rcumult'.
> >> > > >
> >> > > > Signed-off-by: Joel Fernandes (Google) <[email protected]>
> >> > >
> >> > > Applied for testing and review, thank you!
> >> >
> >> > But testing did not go far:
> >> >
> >> > kernel/rcu/tree.c: In function ‘kfree_rcu_shrink_count’:
> >> > kernel/rcu/tree.c:3120:16: warning: unused variable ‘flags’
> >[-Wunused-variable]
> >> > unsigned long flags, count = 0;
> >>
> >> I fixed the warning already but did not resend since it was just the
> >> one unused variable warning. The patches are otherwise good to apply.
> >> Sorry, and I can resend it soon if you are not reapplying right now.
> >
> >So remove "flags, " and all is well?
>
> Yes, that's right. I dropped the lock but forgot to remove it.
Done, thank you!
Thanx, Paul
> >If so, I can just as easily fix that as take a new series. But next
> >time, please give a fella a warning. ;-)
>
> Will do, my bad. Thank you ;-)
>
> - Joel
>
> >
> > Thanx, Paul
>
> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.