linux-kernel - Re: [patch 02/14] x86/apic: Implement single target IPI function for x2apic

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Message-ID: <CA+55aFzGFmGzytS_kDfs8FF=zZ2Y2sXpMNbY+g6EgVfwWEyaBw@mail.gmail.com>
Date:	Wed, 4 Nov 2015 22:46:01 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>, Peter Anvin <hpa@...or.com>,
	Borislav Petkov <borislav.petkov@....com>,
	Peter Zijlstra <peterz@...radead.org>,
	Mike Travis <travis@....com>,
	Daniel J Blueman <daniel@...ascale.com>
Subject: Re: [patch 02/14] x86/apic: Implement single target IPI function for x2apic_cluster

On Wed, Nov 4, 2015 at 10:38 PM, Ingo Molnar <mingo@...nel.org> wrote:
>
> but in the above sequence I think we can do even better: we don't need the
> local_irq_save()/restore() I think.

Right. Thomas added that one to my patch.

I don't think he realized just *how* trivial sending a single IPI is
with the x2apic, and just how horribly nasty the mask case is in
comparison (and how nasty it is that we historically turn a the single
ipi into a mask).

              Linus
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