linux-kernel - Re: [GIT PULL] timer fixes

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Message-ID: <20191217193039.GF2844@hirez.programming.kicks-ass.net>
Date:   Tue, 17 Dec 2019 20:30:39 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [GIT PULL] timer fixes

On Tue, Dec 17, 2019 at 11:14:48AM -0800, Linus Torvalds wrote:
> On Tue, Dec 17, 2019 at 3:55 AM Ingo Molnar <mingo@...nel.org> wrote:
> >
> > Add HPET quirks for the Intel "Coffee Lake H" and "Ice Lake" platforms.
> 
> Is there any reason we don't force-disable HPET by default if there
> are alternatives?

What alternatives are there? That is, we normally only use HPET to
double check nobody messed up the TSC.

Now it (fingers crossed) seems to be getting better in that more recent
firmware is less likely to wreck TSC, but we're still running this on
plenty of old machines where TSC really isn't all that sane.

We can't just blindly trust TSC across everything x86.