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From: Joel Fernandes <joelaf@google.com>
To: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-rt-users <linux-rt-users@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Tom Zanussi <tom.zanussi@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Boqun Feng <boqun.feng@gmail.com>, fweisbec <fweisbec@gmail.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	kbuild test robot <fengguang.wu@intel.com>,
	baohong liu <baohong.liu@intel.com>,
	vedang patel <vedang.patel@intel.com>,
	kernel-team <kernel-team@lge.com>
Subject: Re: [RFC v4 3/4] irqflags: Avoid unnecessary calls to trace_ if you can
Date: Tue, 24 Apr 2018 12:01:17 -0700	[thread overview]
Message-ID: <CAJWu+oosc4_X3qqx8tUEKR+g0gCdZQwBi7H6NXDdpu6HGG6MJg@mail.gmail.com> (raw)
In-Reply-To: <CAJWu+opC9pLxoiXq7QDRUDe6ouC4ij398bHCfnUwp+h7Y_ssDg@mail.gmail.com>

On Tue, Apr 24, 2018 at 11:59 AM, Joel Fernandes <joelaf@google.com> wrote:
[...]
>>> > > By the way is there any limitation on using SRCU too early during
>>> > > boot? I backported Mathieu's srcu tracepoint patches but the kernel
>>> > > hangs pretty early in the boot. I register lockdep probes in
>>> > > start_kernel. I am hoping that's not why.
>>> > >
>>> > > I could also have just screwed up the backporting... may be for my
>>> > > testing, I will just replace the rcu API with the srcu instead of all
>>> > > of Mathieu's new TRACE_EVENT macros for SRCU, since all I am trying to
>>> > > do right now is measure the performance of my patches with SRCU.
>>> >
>>> > Gah, yes, there is an entry on my capacious todo list on making SRCU
>>> > grace periods work during early boot and mid-boot.  Let me see what
>>> > I can do...
>>>
>>> OK, just need to verify that you are OK with call_srcu()'s callbacks
>>> not being invoked until sometime during core_initcall() time.  (If you
>>> really do need them to be invoked before that, in theory it is possible,
>>> but in practice it is weird, even for RCU.)
>>
>> Oh, and that early at boot, you will need to use DEFINE_SRCU() or
>> DEFINE_STATIC_SRCU() rather than dynamic allocation and initialization.
>>
>>                                                         Thanx, Paul
>>
>
> Oh ok.
>
> About call_rcu, calling it later may be an issue since we register the
> probes in start_kernel, for the first probe call_rcu will be sched,

Sorry, I need to start proof reading my emails. s/sched/skipped/

thanks,

- Joel

  reply	other threads:[~2018-04-24 19:01 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17  4:07 [RFC v4 0/4] Centralize and unify usage of preempt/irq tracepoints Joel Fernandes
2018-04-17  4:07 ` [RFC v4 1/4] tracepoint: Add API to not do lockdep checks during RCU ops Joel Fernandes
2018-04-17  4:07 ` [RFC v4 2/4] softirq: reorder trace_softirqs_on to prevent lockdep splat Joel Fernandes
2018-04-17  4:07 ` [RFC v4 3/4] irqflags: Avoid unnecessary calls to trace_ if you can Joel Fernandes
2018-04-18  9:02   ` Masami Hiramatsu
2018-04-19  5:43     ` Namhyung Kim
2018-04-20  7:07       ` Joel Fernandes
2018-04-23  1:14         ` Joel Fernandes
2018-04-23  3:19           ` Paul E. McKenney
2018-04-23 14:31             ` Mathieu Desnoyers
2018-04-23 14:53               ` Steven Rostedt
2018-04-23 14:59                 ` Mathieu Desnoyers
2018-04-23 15:12                   ` Paul E. McKenney
2018-04-23 16:18                   ` Steven Rostedt
2018-04-23 17:12                     ` Mathieu Desnoyers
2018-04-23 17:24                       ` Joel Fernandes
2018-04-23 21:22                       ` Steven Rostedt
2018-04-24 15:56                         ` Paul E. McKenney
2018-04-24 16:01                           ` Joel Fernandes
2018-04-24 17:26                             ` Paul E. McKenney
2018-04-24 18:23                               ` Paul E. McKenney
2018-04-24 18:26                                 ` Paul E. McKenney
2018-04-24 18:59                                   ` Joel Fernandes
2018-04-24 19:01                                     ` Joel Fernandes [this message]
2018-04-24 19:09                                     ` Paul E. McKenney
2018-04-24 19:16                                       ` Joel Fernandes
2018-04-24 23:21                                     ` Mathieu Desnoyers
2018-04-24 23:46                                       ` Joel Fernandes
2018-04-25  0:10                                         ` Paul E. McKenney
2018-04-25  4:20                                           ` Paul E. McKenney
2018-04-25 21:27                                             ` Joel Fernandes
2018-04-25 21:35                                               ` Paul E. McKenney
2018-04-25 21:40                                               ` Mathieu Desnoyers
2018-04-25 22:51                                                 ` Steven Rostedt
2018-04-26 15:03                                                   ` Mathieu Desnoyers
2018-04-26 16:08                                                     ` Mathieu Desnoyers
2018-04-25 23:13                                                 ` Joel Fernandes
2018-04-26 15:13                                                   ` Mathieu Desnoyers
2018-04-26 15:20                                                     ` Joel Fernandes
2018-04-26 15:49                                                     ` Paul E. McKenney
2018-04-23 15:49                 ` Joel Fernandes
2018-04-26  2:18             ` Joel Fernandes
2018-05-01  1:18     ` Joel Fernandes
2018-04-17  4:07 ` [RFC v4 4/4] tracing: Centralize preemptirq tracepoints and unify their usage Joel Fernandes

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