From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>, Borislav Petkov <bp@alien8.de>
Cc: tony.luck@intel.com, mingo@redhat.com, hpa@zytor.com,
x86@kernel.org, linux-edac@vger.kernel.org,
linux-kernel@vger.kernel.org,
Chris Wilson <chris@chris-wilson.co.uk>
Subject: Re: [PATCH] x86/mce/therm_throt: Handle case where throttle_active_work() is called on behalf of an offline CPU
Date: Tue, 25 Feb 2020 01:46:43 -0800 [thread overview]
Message-ID: <9edd2470285db5cf38556d00cfc56215069b2d4c.camel@linux.intel.com> (raw)
In-Reply-To: <87lforn5xr.fsf@nanos.tec.linutronix.de>
On Mon, 2020-02-24 at 20:25 +0100, Thomas Gleixner wrote:
> Thomas Gleixner <tglx@linutronix.de> writes:
> > Which is wrong as well. Trying to "fix" it in the work queue
> > callback is
> > papering over the root cause.
> >
> > Why is any work scheduled on an outgoing CPU after this CPU
> > executed
> > thermal_throttle_offline()?
> >
> > When thermal_throttle_offline() is invoked the cpu bound work
> > queues are
> > still functional and thermal_throttle_offline() cancels outstanding
> > work.
> >
> > So no, please fix the root cause not the symptom.
>
> And if you look at thermal_throttle_online() then you'll notice that
> it
> is asymetric vs. thermal_throttle_offline().
>
> Also you want to do cancel_delayed_work_sync() and not just
> cancel_delayed_work() because only the latter guarantees that the
> work
> is not enqueued anymore while the former does not take running or
> self
> requeueing work into account.
>
> Something like the untested patch below.
I tested this patch.
After simulating 20 million thermal interrupts and online/offline test
for 12+ hours, don't see the issue.
So this change fixed the issue.
I can send change on your behalf or you can add
Tested-by: Pandruvada, Srinivas <srinivas.pandruvada@linux.intel.com>
Thanks,
Srinivas
>
> Thanks,
>
> tglx
> ---
> --- a/arch/x86/kernel/cpu/mce/therm_throt.c
> +++ b/arch/x86/kernel/cpu/mce/therm_throt.c
> @@ -487,8 +487,12 @@ static int thermal_throttle_offline(unsi
> struct thermal_state *state = &per_cpu(thermal_state, cpu);
> struct device *dev = get_cpu_device(cpu);
>
> - cancel_delayed_work(&state->package_throttle.therm_work);
> - cancel_delayed_work(&state->core_throttle.therm_work);
> + /* Mask the thermal vector before draining evtl. pending work
> */
> + l = apic_read(APIC_LVTTHMR);
> + apic_write(APIC_LVTTHMR, l | APIC_LVT_MASKED);
> +
> + cancel_delayed_work_sync(&state->package_throttle.therm_work);
> + cancel_delayed_work_sync(&state->core_throttle.therm_work);
>
> state->package_throttle.rate_control_active = false;
> state->core_throttle.rate_control_active = false;
prev parent reply other threads:[~2020-02-25 9:46 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-22 16:24 [PATCH] x86/mce/therm_throt: Handle case where throttle_active_work() is called on behalf of an offline CPU Srinivas Pandruvada
2020-02-22 16:53 ` Chris Wilson
2020-02-22 17:51 ` Borislav Petkov
2020-02-23 0:25 ` Srinivas Pandruvada
2020-02-24 12:55 ` Borislav Petkov
2020-02-24 16:01 ` Thomas Gleixner
2020-02-24 19:25 ` Thomas Gleixner
2020-02-24 21:05 ` Pandruvada, Srinivas
2020-02-25 9:46 ` Srinivas Pandruvada [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9edd2470285db5cf38556d00cfc56215069b2d4c.camel@linux.intel.com \
--to=srinivas.pandruvada@linux.intel.com \
--cc=bp@alien8.de \
--cc=chris@chris-wilson.co.uk \
--cc=hpa@zytor.com \
--cc=linux-edac@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).