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Date: Mon, 3 Nov 2014 22:47:12 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Jan Beulich <jbeulich@suse.com>, Ingo Molnar <mingo@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        Chuck Ebbert <cebbert.lkml@gmail.com>, Anish Bhatt <anish@chelsio.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "linux-tip-commits@vger.kernel.org" 
	<linux-tip-commits@vger.kernel.org>
Subject: Re: [tip:x86/asm] sched/x86_64: Don't save flags on context switch
Message-ID: <20141103214712.GA8711@redhat.com>
References: <bf6fb790787eb95b922157838f52712c25dda157.1412187233.git.luto@amacapital.net> <tip-2c7577a7583747c9b71f26dced7f696b739da745@git.kernel.org> <CALCETrWM2wVynp1rrip9AWtNYDzjC4M8JqKR82ew5dpyrTWMgA@mail.gmail.com>
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On 11/03, Andy Lutomirski wrote:
>
> And do we ever have TF set during a context switch?  I hope not.

I too hope.

> Also, what's with 'jmp exit_intr' at the end of retint_kernel?  Why
> isn't that 'jmp retint_kernel'?

Even better, why not "jmp retint_restore_args" ?

preempt_schedule_irq() checks need_resched() and returns with irqs
disabled, not need to to recheck test_preempt_need_resched() ?

Oleg.