From: John Ogness <john.ogness@linutronix.de>
To: paulmck@kernel.org
Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, rostedt@goodmis.org,
Thomas Gleixner <tglx@linutronix.de>,
Petr Mladek <pmladek@suse.com>
Subject: Re: [PATCH RFC v2 rcu 1/8] srcu: Convert ->srcu_lock_count and ->srcu_unlock_count to atomic
Date: Fri, 30 Sep 2022 22:43:43 +0206 [thread overview]
Message-ID: <87wn9k7g4o.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <20220930153506.GD4196@paulmck-ThinkPad-P17-Gen-1>
On 2022-09-30, "Paul E. McKenney" <paulmck@kernel.org> wrote:
>> > - this_cpu_inc(ssp->sda->srcu_lock_count[idx]);
>> > + this_cpu_inc(ssp->sda->srcu_lock_count[idx].counter);
>>
>> Is there any particular reason that you are directly modifying
>> @counter instead of raw_cpu_ptr()+atomic_long_inc() that do you in
>> __srcu_read_lock_nmisafe() of patch 2?
>
> Performance. From what I can see, this_cpu_inc() is way faster than
> atomic_long_inc() on x86 and s390. Maybe also on loongarch. No idea
> on arm64.
Yeah, that's what I figured. I just wanted to make sure.
FWIW, the rest of the series looks pretty straight forward to me.
John
next prev parent reply other threads:[~2022-09-30 20:37 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-21 14:46 [PATCH rcu 0/4] NMI-safe SRCU reader API Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 1/4] srcu: Convert ->srcu_lock_count and ->srcu_unlock_count to atomic Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 2/4] srcu: Create and srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe() Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 3/4] srcu: Check for consistent per-CPU per-srcu_struct NMI safety Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 4/4] srcu: Check for consistent global " Paul E. McKenney
2022-09-29 18:07 ` [PATCH v2 rcu 0/8] NMI-safe SRCU reader API Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 1/8] srcu: Convert ->srcu_lock_count and ->srcu_unlock_count to atomic Paul E. McKenney
2022-09-30 15:02 ` John Ogness
2022-09-30 15:35 ` Paul E. McKenney
2022-09-30 20:37 ` John Ogness [this message]
2022-10-01 16:51 ` Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 2/8] srcu: Create an srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe() Paul E. McKenney
2022-10-02 15:55 ` Frederic Weisbecker
2022-10-02 15:57 ` Frederic Weisbecker
2022-10-02 16:10 ` Paul E. McKenney
2022-10-02 16:09 ` Paul E. McKenney
2022-10-02 21:47 ` Frederic Weisbecker
2022-10-02 23:46 ` Paul E. McKenney
2022-10-03 9:55 ` Frederic Weisbecker
2022-10-03 11:52 ` Paul E. McKenney
2022-10-18 14:31 ` John Ogness
2022-10-18 15:18 ` Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 3/8] srcu: Check for consistent per-CPU per-srcu_struct NMI safety Paul E. McKenney
2022-10-02 22:06 ` Frederic Weisbecker
2022-10-02 23:51 ` Paul E. McKenney
2022-10-03 10:13 ` Frederic Weisbecker
2022-10-03 11:57 ` Paul E. McKenney
2022-10-03 12:37 ` Frederic Weisbecker
2022-10-03 13:32 ` Paul E. McKenney
2022-10-03 13:36 ` Frederic Weisbecker
2022-09-29 18:07 ` [PATCH RFC v2 rcu 4/8] srcu: Check for consistent global " Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 5/8] arch/x86: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 6/8] arch/arm64: " Paul E. McKenney
2022-09-29 18:07 ` Paul E. McKenney
2022-10-05 11:12 ` Mark Rutland
2022-10-05 11:12 ` Mark Rutland
2022-09-29 18:07 ` [PATCH RFC v2 rcu 7/8] arch/loongarch: " Paul E. McKenney
2022-09-29 18:07 ` [PATCH RFC v2 rcu 8/8] arch/s390: " Paul E. McKenney
2022-10-03 14:11 ` [PATCH v2 rcu 0/8] NMI-safe SRCU reader API Frederic Weisbecker
2022-10-03 16:38 ` Paul E. McKenney
2022-10-14 22:47 ` Joel Fernandes
2022-10-14 22:52 ` Joel Fernandes
2022-10-18 10:33 ` John Ogness
2022-10-18 15:24 ` Paul E. McKenney
2022-10-18 18:44 ` John Ogness
2022-10-18 18:59 ` Paul E. McKenney
2022-10-18 21:57 ` Paul E. McKenney
2022-10-19 11:13 ` John Ogness
2022-10-19 19:14 ` Paul E. McKenney
2022-10-19 21:38 ` John Ogness
2022-10-19 22:05 ` Frederic Weisbecker
2022-10-20 22:27 ` Paul E. McKenney
2022-10-20 22:41 ` Paul E. McKenney
2022-10-21 12:27 ` John Ogness
2022-10-21 13:59 ` Paul E. McKenney
2022-10-21 18:41 ` Paul E. McKenney
2022-10-24 6:15 ` John Ogness
2022-10-24 13:47 ` Paul E. McKenney
2022-10-27 9:31 ` John Ogness
2022-10-27 14:10 ` Paul E. McKenney
2022-10-27 14:39 ` John Ogness
2022-10-27 16:01 ` Paul E. McKenney
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