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From: Gao Xiang <hsiangkao@linux.alibaba.com>
To: paulmck@kernel.org
Cc: Joel Fernandes <joel@joelfernandes.org>,
	Sandeep Dhavale <dhavale@google.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Neeraj Upadhyay <quic_neeraju@quicinc.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Zqiang <qiang.zhang1211@gmail.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	AngeloGioacchino Del Regno
	<angelogioacchino.delregno@collabora.com>,
	linux-erofs@lists.ozlabs.org, xiang@kernel.org,
	Will Shiu <Will.Shiu@mediatek.com>,
	kernel-team@android.com, rcu@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [PATCH v1] rcu: Fix and improve RCU read lock checks when !CONFIG_DEBUG_LOCK_ALLOC
Date: Thu, 13 Jul 2023 12:59:27 +0800	[thread overview]
Message-ID: <f1c60dcb-e32f-7b7e-bf0d-5dec999e9299@linux.alibaba.com> (raw)
In-Reply-To: <87292a44-cc02-4d95-940e-e4e31d0bc6f2@paulmck-laptop>



On 2023/7/13 12:52, Paul E. McKenney wrote:
> On Thu, Jul 13, 2023 at 12:41:09PM +0800, Gao Xiang wrote:
>>
>>

...

>>
>> There are lots of performance issues here and even a plumber
>> topic last year to show that, see:
>>
>> [1] https://lore.kernel.org/r/20230519001709.2563-1-tj@kernel.org
>> [2] https://lore.kernel.org/r/CAHk-=wgE9kORADrDJ4nEsHHLirqPCZ1tGaEPAZejHdZ03qCOGg@mail.gmail.com
>> [3] https://lore.kernel.org/r/CAB=BE-SBtO6vcoyLNA9F-9VaN5R0t3o_Zn+FW8GbO6wyUqFneQ@mail.gmail.com
>> [4] https://lpc.events/event/16/contributions/1338/
>> and more.
>>
>> I'm not sure if it's necessary to look info all of that,
>> andSandeep knows more than I am (the scheduling issue
>> becomes vital on some aarch64 platform.)
> 
> Hmmm...  Please let me try again.
> 
> Assuming that this approach turns out to make sense, the resulting
> patch will need to clearly state the performance benefits directly in
> the commit log.
> 
> And of course, for the approach to make sense, it must avoid breaking
> the existing lockdep-RCU debugging code.
> 
> Is that more clear?

Personally I'm not working on Android platform any more so I don't
have a way to reproduce, hopefully Sandeep could give actually
number _again_ if dm-verity is enabled and trigger another
workqueue here and make a comparsion why the scheduling latency of
the extra work becomes unacceptable.

Thanks,
Gao Xiang

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  reply	other threads:[~2023-07-13  5:00 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-11 23:38 [PATCH v1] rcu: Fix and improve RCU read lock checks when !CONFIG_DEBUG_LOCK_ALLOC Sandeep Dhavale
2023-07-12 17:02 ` Joel Fernandes
2023-07-12 21:20   ` Sandeep Dhavale
2023-07-13  0:32     ` Joel Fernandes
2023-07-13  2:02       ` Gao Xiang
2023-07-13  2:10         ` Gao Xiang
2023-07-13  2:16         ` Joel Fernandes
2023-07-13  4:27         ` Paul E. McKenney
2023-07-13  4:41           ` Gao Xiang
2023-07-13  4:52             ` Paul E. McKenney
2023-07-13  4:59               ` Gao Xiang [this message]
2023-07-13 14:07                 ` Joel Fernandes
2023-07-13 14:34                   ` Gao Xiang
2023-07-13 15:33                     ` Joel Fernandes
2023-07-13 16:09                       ` Alan Huang
2023-07-13 18:14                         ` Paul E. McKenney
2023-07-13 19:00                           ` Gao Xiang
2023-07-13 22:27                             ` Paul E. McKenney
2023-07-13 16:33                       ` Paul E. McKenney
2023-07-13 17:05                         ` Sandeep Dhavale
2023-07-13 17:35                           ` Paul E. McKenney
2023-07-13 18:51                             ` Sandeep Dhavale
2023-07-13 22:49                               ` Paul E. McKenney
2023-07-13 23:08                                 ` Sandeep Dhavale
2023-07-13 23:28                                   ` Paul E. McKenney
2023-07-14  2:16                         ` Paul E. McKenney
2023-07-14  3:16                           ` Gao Xiang
2023-07-14 13:42                             ` Joel Fernandes
2023-07-14 13:51                               ` Gao Xiang
2023-07-14 14:56                                 ` Steven Rostedt
2023-07-14 15:13                                   ` Paul E. McKenney
2023-07-14 15:35                           ` Alan Huang
2023-07-14 15:54                             ` Alan Huang
2023-07-14 17:02                               ` Paul E. McKenney
2023-07-14 18:40                                 ` Alan Huang
2023-07-14 18:44                                   ` Paul E. McKenney
2023-07-14 19:15                                     ` Sandeep Dhavale
2023-07-14 19:36                                       ` Paul E. McKenney
2023-07-13  4:51           ` Gao Xiang

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