linux-kernel - Re: [4.2, Regression] Queued spinlocks cause major XFS performance regression

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Date:	Wed, 09 Sep 2015 22:06:10 -0400
From:	Waiman Long <waiman.long@....com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dave Chinner <david@...morbit.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Waiman Long <Waiman.Long@...com>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [4.2, Regression] Queued spinlocks cause major XFS performance
 regression

On 09/04/2015 11:54 AM, Peter Zijlstra wrote:
> On Fri, Sep 04, 2015 at 05:30:35PM +0200, Peter Zijlstra wrote:
>> Should I place the virt_spin_lock() thing under CONFIG_PARAVIRT (maybe
>> even _SPINLOCKS) such that only paravirt enabled kernels when ran on a
>> hypervisor that does not support paravirt patching (HyperV, VMware,
>> etc..) revert to the test-and-set?
> Ah, CONFIG_HYPERVISOR_GUEST seems fitting, that's a prerequisite for all
> the PARAVIRT options too.
>

Yes, I also used that in my queued unfair lock patch.

Cheers,
Longman
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