linux-kernel - Re: tty breakage in X (Was: tty vs workqueue oddities)

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Message-ID: <BANLkTim6VsynZHLagcu9Xo3EjsUz=54dYA@mail.gmail.com>
Date:	Fri, 3 Jun 2011 18:36:54 +0900
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>, gregkh@...e.de,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Felipe Balbi <balbi@...com>, Tejun Heo <tj@...nel.org>
Subject: Re: tty breakage in X (Was: tty vs workqueue oddities)

On Fri, Jun 3, 2011 at 3:56 PM, Benjamin Herrenschmidt
<benh@...nel.crashing.org> wrote:
>
> So I think my theory stands that flush_to_ldisc constantly reschedule
> itself causing the worker thread to eat all CPU and starve the consumer
> of the PTY. I won't have time to dig much deeper today nor probably this
> week-end so I'm sending this email for others who want to look.

Gaah - that commit is total and utter crap.

I *removed* the whole "reschedule the work queue again" crap. It was
totally wrong. See commit a5660b41af6a.

But then commit b1c43f82c5aa added the crap right back in.

So does it all work if you just remove the broken schedule_work() line
from flush_to_ldisc?

Otherwise we'll need to just revert it. The commit is clearly totally broken.

                    Linus
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