linux-kernel - Re: [PATCH 2/2][v2] cpuidle-haltpoll: Build as module by default

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Message-ID: <Y5yIWKq5Ggpzvvag@hirez.programming.kicks-ass.net>
Date:   Fri, 16 Dec 2022 16:01:44 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Li,Rongqing" <lirongqing@...du.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "tony.luck@...el.com" <tony.luck@...el.com>,
        "jpoimboe@...nel.org" <jpoimboe@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 2/2][v2] cpuidle-haltpoll: Build as module by default

On Thu, Dec 08, 2022 at 02:32:15AM +0000, Li,Rongqing wrote:
> 
> > > Allow user to unload it in running
> > 
> > Just like that?  And corrupt things left and right while at it?
> > 
> > No way.
> > 
> > And why do you need this?
> 
> Cpuidle-haltpoll can not improve performance for all cases, like when
> guest has mwait, unixbench shows a small performance drop; So change
> it as module, user can insmod this drivers and rmmod this driver at
> run time

I'm thinking all this can be achieved by a small change to
haltpoll_want().