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From: Mike Galbraith <efault@gmx.de>
To: 王擎 <wangqing@vivo.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Michal Hocko <mhocko@kernel.org>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Will Deacon <will@kernel.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Dirk Behme <dirk.behme@de.bosch.com>,
	linux-kernel@vger.kernel.org
Subject: Re: Re: [PATCH,RESEND] softirq: Introduce SOFTIRQ_FORCED_THREADING
Date: Mon, 23 Aug 2021 09:43:58 +0200	[thread overview]
Message-ID: <275a0f09654cf5644cbc5731fa031b218eed6d38.camel@gmx.de> (raw)
In-Reply-To: <AJEACAC1D27qN9TVG8Nujqqw.3.1629700439268.Hmail.wangqing@vivo.com>

On Mon, 2021-08-23 at 14:33 +0800, 王擎 wrote:
>
> > On Mon, 2021-08-23 at 11:33 +0800, Wang Qing wrote:
> > > At present, whether the softirq is executed when the interrupt exits
> > > is controlled by IRQ_FORCED_THREADING. This is unreasonable. It should
> > > be split and allowed to take effect separately.
> >
> > Decades long practice suddenly became "unreasonable"?  I think not.  
>
> "unreasonable" may be my misnomer, but it is really necessary to separate
> softirq from IRQ_FORCED_THREADING, which can be effective separately.

Well, no, it's not necessary, but would be damn convenient to you,
which is of course a perfectly fine motivation to post a patch :)

> >
> > Trying to carve out bits and pieces of RT to merge immediately isn't
> > likely to make the ongoing merge effort go anyfaster or smoother.
>
> I am not trying to carve out bits and pieces of RT, but I encountered actual
> problems in my project. For example, in Android, we will not enable
> IRQ_FORCED_THREADING, Android is not a high real-time requirements,
> but in some scenariossome, RT processes cannot be scheduled in time
> and the frame is dropped due to the execution time of softirq is too long,
> also some softirq cannot be executed in time in ksoftirqs, and delays occur,
> such as IO.

That didn't parse well here.  What you seem to be saying is that you
have a hard constraint that can't be meet, yet are unwilling to use an
existing facility to resolve that issue because the kernel you're using
is not _intended_ to support hard realtime... therefore you want this
other facility to enable it to support your hard realtime requirement.

That can't be right, but it doesn't really matter, because...

> Therefore, why not give the user a choice to balance the execution of softirq
> while not enable IRQ_FORCED_THREADING, so as to meet the inconsistent
> scenes and needs

...it's not my call, I just found the language rather odd.  It still
looks to me like you're carving out a slice of RT.

	-Mike


  reply	other threads:[~2021-08-23  7:44 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23  3:33 Wang Qing
2021-08-23  4:22 ` Mike Galbraith
2021-08-23  6:33   ` 王擎
2021-08-23  7:43     ` Mike Galbraith [this message]
2021-08-27 22:27 ` Thomas Gleixner
2021-08-28  2:18   ` 王擎
2021-08-28 14:07     ` Thomas Gleixner

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