linux-kernel - Re: [RFC] [PATCH] Pre-emption control for userspace

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Message-ID: <20140305163644.GA2824@redhat.com>
Date:	Wed, 5 Mar 2014 17:36:44 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Khalid Aziz <khalid.aziz@...cle.com>,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
	peterz@...radead.org, akpm@...ux-foundation.org,
	viro@...iv.linux.org.uk, linux-kernel@...r.kernel.org
Subject: Re: [RFC] [PATCH] Pre-emption control for userspace

On 03/05, Andi Kleen wrote:
>
> On Wed, Mar 05, 2014 at 03:54:20PM +0100, Oleg Nesterov wrote:
> > On 03/04, Andi Kleen wrote:
> > >
> > > Anything else?
> >
> > Well, we have yield_to(). Perhaps sys_yield_to(lock_owner) can help.
> > Or perhaps sys_futex() can do this if it knows the owner. Don't ask
> > me what exactly I mean though ;)
>
> You mean yield_to() would extend the time slice?
>
> That would be the same as the mmap page, just with a syscall right?

Not the same. Very roughly I meant something like

	my_lock()
	{
		if (!TRY_LOCK()) {
			yield_to(owner);
			LOCK();
		}

		owner = gettid();
	}

But once again, I am not sure if this makes any sense.

Oleg.

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