linux-kernel - Re: [PATCH v4] x86/power: Fix 'nosmt' vs. hibernation triple fault during resume

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Message-ID: <2718594.dmOzsuS6R2@kreacher>
Date:   Mon, 03 Jun 2019 12:03:49 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Jiri Kosina <jikos@...nel.org>,
        Andy Lutomirski <luto@...capital.net>,
        Andy Lutomirski <luto@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        the arch/x86 maintainers <x86@...nel.org>,
        Pavel Machek <pavel@....cz>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] x86/power: Fix 'nosmt' vs. hibernation triple fault during resume

On Friday, May 31, 2019 6:19:52 PM CEST Josh Poimboeuf wrote:
> On Fri, May 31, 2019 at 05:41:18PM +0200, Jiri Kosina wrote:
> > On Fri, 31 May 2019, Josh Poimboeuf wrote:
> > 
> > > The only question I'd have is if we have data on the power savings 
> > > difference between hlt and mwait.  mwait seems to wake up on a lot of 
> > > different conditions which might negate its deeper sleep state.
> > 
> > hlt wakes up on basically the same set of events, but has the 
> > auto-restarting semantics on some of them (especially SMM). So the wakeup 
> > frequency itself shouldn't really contribute to power consumption 
> > difference; it's the C-state that mwait allows CPU to enter.
> 
> Ok.  I reluctantly surrender :-)  For your v4:
> 
>   Reviewed-by: Josh Poimboeuf <jpoimboe@...hat.com>
> 
> It works as a short term fix, but it's fragile, and it does feel like
> we're just adding more duct tape, as Andy said.

OK, the v4 queued up then, thanks!