| Message ID | 20230531101736.12981-6-frederic@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | rcu: Support for lazy callbacks on !CONFIG_RCU_NOCB_CPU | expand |
> From: Frederic Weisbecker <frederic@kernel.org> > Sent: Wednesday, May 31, 2023 6:18 PM > ... > Subject: [PATCH 5/9] rcu: Add rcutree.lazy_enabled boot parameter I didn't find the 'lazy_enabled' variable in the patch series. Did you say rcutree. qhimark_lazy? -Qiuxu > Allow to overwrite the arbitrary default number of lazy callbacks threshold > that is currently set to 100. This allows for tuning between powersaving, > throughtput and memory consumption expectations. As a bonus, setting this > value to 0 disables lazy callbacks. > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org> > --- > Documentation/admin-guide/kernel-parameters.txt | 5 +++++ > kernel/rcu/tree.c | 3 ++- > 2 files changed, 7 insertions(+), 1 deletion(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > b/Documentation/admin-guide/kernel-parameters.txt > index 505978cfb548..dd2be4249061 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -4798,6 +4798,11 @@ > Set threshold of queued RCU callbacks beyond which > batch limiting is disabled. > > + rcutree.qhimark_lazy = [KNL] > + Set threshold of queued lazy RCU callbacks beyond > which > + batch must be flushed to the main queue. If set to 0, > + disable lazy queue. > + > rcutree.qlowmark= [KNL] > Set threshold of queued RCU callbacks below which > batch limiting is re-enabled. > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index > 9b98d87fa22e..e33c0d889216 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -390,6 +390,7 @@ static long qovld_calc = -1; // No pre- > initialization lock acquisitions! > > module_param(blimit, long, 0444); > module_param(qhimark, long, 0444); > +module_param(qhimark_lazy, long, 0444); > module_param(qlowmark, long, 0444); > module_param(qovld, long, 0444); > > @@ -2655,7 +2656,7 @@ __call_rcu_common(struct rcu_head *head, > rcu_callback_t func, bool lazy_in) > kasan_record_aux_stack_noalloc(head); > local_irq_save(flags); > rdp = this_cpu_ptr(&rcu_data); > - lazy = lazy_in && !rcu_async_should_hurry(); > + lazy = lazy_in && qhimark_lazy && !rcu_async_should_hurry(); > > /* Add the callback to our list. */ > if (unlikely(!rcu_segcblist_is_enabled(&rdp->cblist))) { > -- > 2.40.1
Le Tue, Jun 13, 2023 at 06:57:25AM +0000, Zhuo, Qiuxu a écrit : > > From: Frederic Weisbecker <frederic@kernel.org> > > Sent: Wednesday, May 31, 2023 6:18 PM > > ... > > Subject: [PATCH 5/9] rcu: Add rcutree.lazy_enabled boot parameter > > I didn't find the 'lazy_enabled' variable in the patch series. > Did you say rcutree. qhimark_lazy? Indeed :-) Thanks.
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 505978cfb548..dd2be4249061 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4798,6 +4798,11 @@ Set threshold of queued RCU callbacks beyond which batch limiting is disabled. + rcutree.qhimark_lazy = [KNL] + Set threshold of queued lazy RCU callbacks beyond which + batch must be flushed to the main queue. If set to 0, + disable lazy queue. + rcutree.qlowmark= [KNL] Set threshold of queued RCU callbacks below which batch limiting is re-enabled. diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 9b98d87fa22e..e33c0d889216 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -390,6 +390,7 @@ static long qovld_calc = -1; // No pre-initialization lock acquisitions! module_param(blimit, long, 0444); module_param(qhimark, long, 0444); +module_param(qhimark_lazy, long, 0444); module_param(qlowmark, long, 0444); module_param(qovld, long, 0444); @@ -2655,7 +2656,7 @@ __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy_in) kasan_record_aux_stack_noalloc(head); local_irq_save(flags); rdp = this_cpu_ptr(&rcu_data); - lazy = lazy_in && !rcu_async_should_hurry(); + lazy = lazy_in && qhimark_lazy && !rcu_async_should_hurry(); /* Add the callback to our list. */ if (unlikely(!rcu_segcblist_is_enabled(&rdp->cblist))) {
Allow to overwrite the arbitrary default number of lazy callbacks threshold that is currently set to 100. This allows for tuning between powersaving, throughtput and memory consumption expectations. As a bonus, setting this value to 0 disables lazy callbacks. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> --- Documentation/admin-guide/kernel-parameters.txt | 5 +++++ kernel/rcu/tree.c | 3 ++- 2 files changed, 7 insertions(+), 1 deletion(-)