linux-kernel - Re: [PATCH] locking/paravirt: Fix performance regression on core bonded vCPU

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Date:   Thu, 3 Nov 2022 14:22:44 +0100
From:   Juergen Gross <jgross@...e.com>
To:     johnnyaiai <arafatms@...look.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        johnnyaiai <johnnyaiai@...cent.com>
Subject: Re: [PATCH] locking/paravirt: Fix performance regression on core
 bonded vCPU

On 03.11.22 13:13, johnnyaiai wrote:
> From: johnnyaiai <johnnyaiai@...cent.com>
> 
> virt_spin_lock() is preferred over native qspinlock when
> vCPU is preempted. But brings a lot of regression while
> vCPU is not preempted. Provide a early param 'novirtlock'
> to choose would be better.
> 
> will-it-scale/lock2_threads -s 10 -t 64
> baseline    afterpatch
> 559938       2166135
> 
> Signed-off-by: johnnyaiai <johnnyaiai@...cent.com>

That is exactly the purpose of the existing nopvspin parameter.


Juergen

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