linux-kernel - Re: [PATCH 0/6] x86: reduce paravirtualized spinlock overhead

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Date:	Thu, 30 Apr 2015 09:39:54 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
	x86@...nel.org, hpa@...or.com, tglx@...utronix.de,
	mingo@...hat.com, xen-devel@...ts.xensource.com,
	konrad.wilk@...cle.com, david.vrabel@...rix.com,
	boris.ostrovsky@...cle.com, chrisw@...s-sol.org,
	akataria@...are.com, rusty@...tcorp.com.au,
	virtualization@...ts.linux-foundation.org, gleb@...nel.org,
	pbonzini@...hat.com, kvm@...r.kernel.org
Subject: Re: [PATCH 0/6] x86: reduce paravirtualized spinlock overhead

On 04/30/2015 03:53 AM, Juergen Gross wrote:
> Paravirtualized spinlocks produce some overhead even if the kernel is
> running on bare metal. The main reason are the more complex locking
> and unlocking functions. Especially unlocking is no longer just one
> instruction but so complex that it is no longer inlined.
>
> This patch series addresses this issue by adding two more pvops
> functions to reduce the size of the inlined spinlock functions. When
> running on bare metal unlocking is again basically one instruction.

Out of curiosity, is there a measurable difference?

    J

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