From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Kyle Huey <khuey@kylehuey.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [patch 1/3] x86/process: Optimize TIF checks in switch_to_extra()
Date: Thu, 15 Dec 2016 18:26:28 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1612151826120.3470@nanos> (raw)
In-Reply-To: <20161215172015.GZ3124@twins.programming.kicks-ass.net>
On Thu, 15 Dec 2016, Peter Zijlstra wrote:
> On Thu, Dec 15, 2016 at 04:44:02PM -0000, Thomas Gleixner wrote:
> > void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
> > struct tss_struct *tss)
> > {
> > struct thread_struct *prev, *next;
> > + unsigned long tifp, tifn;
> >
> > prev = &prev_p->thread;
> > next = &next_p->thread;
> >
> > + tifn = task_thread_info(next_p)->flags;
> > + tifp = task_thread_info(prev_p)->flags;
> > + switch_to_bitmap(tss, prev, next, tifp, tifn);
> > +
> > + propagate_user_return_notify(prev_p, next_p);
> > +
> > + if ((tifp ^ tifn) & _TIF_BLOCKSTEP) {
> > unsigned long debugctl = get_debugctlmsr();
> >
> > debugctl &= ~DEBUGCTLMSR_BTF;
> > + if (tifn & _TIF_BLOCKSTEP)
> > debugctl |= DEBUGCTLMSR_BTF;
> > update_debugctlmsr(debugctl);
> > }
>
> Going by the toggle patter you have elsewhere, wouldn't that then be:
>
> if ((tifp ^ tifn) & _TIF_BLOCKSTEP) {
> unsigned long debugctl = get_debugctlmsr();
>
> debugctl ^= DEBUGCTLMSR_BTF;
> update_debugctlmsr(debugctl);
> }
See the next patch
next prev parent reply other threads:[~2016-12-15 17:29 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-15 16:44 [patch 0/3] x86/process: Optimize __switch_to_extra() Thomas Gleixner
2016-12-15 16:44 ` [patch 2/3] x86/process: Optimize TIF_BLOCKSTEP switch Thomas Gleixner
2016-12-15 17:28 ` Andy Lutomirski
2016-12-16 8:47 ` Thomas Gleixner
2016-12-16 19:22 ` Andy Lutomirski
2016-12-15 16:44 ` [patch 1/3] x86/process: Optimize TIF checks in switch_to_extra() Thomas Gleixner
2016-12-15 17:20 ` Peter Zijlstra
2016-12-15 17:26 ` Thomas Gleixner [this message]
2016-12-15 17:33 ` Peter Zijlstra
2016-12-15 17:24 ` Andy Lutomirski
2016-12-15 16:44 ` [patch 3/3] x86/process: Optimize TIF_NOTSC switch Thomas Gleixner
2016-12-15 17:31 ` Andy Lutomirski
2016-12-16 8:50 ` Thomas Gleixner
2016-12-16 18:34 ` Andy Lutomirski
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