From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Jan Kara <jack@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
akpm@linux-foundation.org, jack@suse.com, pmladek@suse.com,
tj@kernel.org, linux-kernel@vger.kernel.org,
sergey.senozhatsky@gmail.com
Subject: Re: [RFC][PATCH v2 1/2] printk: Make printk() completely async
Date: Mon, 7 Mar 2016 23:40:51 +0900 [thread overview]
Message-ID: <20160307144051.GB835@swordfish> (raw)
In-Reply-To: <20160307105248.GF5201@quack.suse.cz>
On (03/07/16 11:52), Jan Kara wrote:
[..]
> So for UP systems, we should by default disable async printing anyway I
> suppose. It is just a pointless overhead. So please just make printk_sync
> default to true if !CONFIG_SMP.
ok, thanks.
> When IRQs are disabled, you're right we will have a change in behavior. I
> don't see an easy way of avoiding delaying of printk until IRQs get
> enabled. I don't want to queue work directly because that creates
> possibility for lock recursion in queue_work(). And playing some tricks
> with irq_works isn't easy either - you cannot actually rely on any other
> CPU doing anything (even a timer tick) because of NOHZ.
yes. I thought about some sort of PRINTK_IPI on smp, and queue work from
PRINTK_IPI. which is a bit insane.
> So if this will be a problem in practice, using a kthread will probably be
> the easiest solution.
probably kthread is the way to go then. Tetsuo's bad experience with
workqueues also sounds a bit alarming.
I'll post a new patch soon.
-ss
next prev parent reply other threads:[~2016-03-07 14:43 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-05 10:55 [RFC][PATCH v2 0/2] printk: Make printk() completely async Sergey Senozhatsky
2016-03-05 10:55 ` [RFC][PATCH v2 1/2] " Sergey Senozhatsky
2016-03-06 6:32 ` Sergey Senozhatsky
2016-03-06 7:18 ` Tetsuo Handa
2016-03-06 9:35 ` Sergey Senozhatsky
2016-03-06 11:06 ` Tetsuo Handa
2016-03-06 13:27 ` Sergey Senozhatsky
2016-03-06 14:54 ` Tetsuo Handa
2016-03-07 8:22 ` Jan Kara
2016-03-07 10:12 ` Sergey Senozhatsky
2016-03-07 10:52 ` Jan Kara
2016-03-07 12:16 ` Jan Kara
2016-03-07 12:37 ` Tetsuo Handa
2016-03-07 15:10 ` Sergey Senozhatsky
2016-03-07 15:49 ` Tejun Heo
2016-03-08 10:21 ` Sergey Senozhatsky
2016-03-11 17:22 ` Tejun Heo
2016-03-12 5:01 ` Sergey Senozhatsky
2016-03-09 6:09 ` Sergey Senozhatsky
2016-03-10 9:27 ` Jan Kara
2016-03-10 15:48 ` Sergey Senozhatsky
2016-03-10 9:53 ` Petr Mladek
2016-03-10 16:26 ` Sergey Senozhatsky
2016-03-07 14:40 ` Sergey Senozhatsky [this message]
2016-03-07 11:10 ` Tetsuo Handa
2016-03-07 14:36 ` Sergey Senozhatsky
2016-03-07 15:42 ` Tejun Heo
2016-03-05 10:55 ` [RFC][PATCH v2 2/2] printk: Skip messages on oops Sergey Senozhatsky
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