IOMMU Archive on lore.kernel.org
 help / color / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ricardo Neri <ricardo.neri@intel.com>,
	Stephane Eranian <eranian@google.com>,
	Kai-Heng Feng <kai.heng.feng@canonical.com>,
	Ingo Molnar <mingo@kernel.org>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Ashok Raj <ashok.raj@intel.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	x86@kernel.org, "Luis R. Rodriguez" <mcgrof@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Andi Kleen <andi.kleen@intel.com>,
	Waiman Long <longman@redhat.com>, Borislav Petkov <bp@suse.de>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Don Zickus <dzickus@redhat.com>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Byungchul Park <byungchul.park@lge.com>,
	Babu Moger <Babu.Moger@amd.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Tony Luck <tony.luck@intel.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	Jacob Pan <jacob.jun.pan@intel.com>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Colin Ian King <colin.king@canonical.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH v4 12/21] watchdog/hardlockup/hpet: Adjust timer expiration on the number of monitored CPUs
Date: Tue, 11 Jun 2019 22:11:04 +0200 (CEST)
Message-ID: <alpine.DEB.2.21.1906112205170.2214@nanos.tec.linutronix.de> (raw)
In-Reply-To: <1558660583-28561-13-git-send-email-ricardo.neri-calderon@linux.intel.com>

On Thu, 23 May 2019, Ricardo Neri wrote:
> @@ -52,10 +59,10 @@ static void kick_timer(struct hpet_hld_data *hdata, bool force)
>  		return;
>  
>  	if (hdata->has_periodic)
> -		period = watchdog_thresh * hdata->ticks_per_second;
> +		period = watchdog_thresh * hdata->ticks_per_cpu;
>  
>  	count = hpet_readl(HPET_COUNTER);
> -	new_compare = count + watchdog_thresh * hdata->ticks_per_second;
> +	new_compare = count + watchdog_thresh * hdata->ticks_per_cpu;
>  	hpet_set_comparator(hdata->num, (u32)new_compare, (u32)period);

So with this you might get close to the point where you trip over the SMI
induced madness where CPUs vanish for several milliseconds in some value
add code. You really want to do a read back of the hpet to detect that. See
the comment in the hpet code. RHEL 7/8 allow up to 768 logical CPUs....

Thanks,

	tglx
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply index

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-24  1:16 [RFC PATCH v4 00/21] Implement an HPET-based hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 01/21] x86/msi: Add definition for NMI delivery mode Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 02/21] x86/hpet: Expose hpet_writel() in header Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 03/21] x86/hpet: Calculate ticks-per-second in a separate function Ricardo Neri
2019-06-14 15:54   ` Thomas Gleixner
2019-06-14 15:59     ` Thomas Gleixner
2019-06-18 22:48     ` Ricardo Neri
2019-06-18 23:13       ` Thomas Gleixner
2019-05-24  1:16 ` [RFC PATCH v4 04/21] x86/hpet: Add hpet_set_comparator() for periodic and one-shot modes Ricardo Neri
2019-06-14 18:17   ` Thomas Gleixner
2019-06-18 22:48     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 05/21] x86/hpet: Reserve timer for the HPET hardlockup detector Ricardo Neri
2019-06-11 19:54   ` Thomas Gleixner
2019-06-14  1:14     ` Ricardo Neri
2019-06-14 16:10       ` Thomas Gleixner
2019-06-18 22:48         ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 06/21] x86/hpet: Configure the timer used by the " Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 07/21] watchdog/hardlockup: Define a generic function to detect hardlockups Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 08/21] watchdog/hardlockup: Decouple the hardlockup detector from perf Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 09/21] x86/nmi: Add a NMI_WATCHDOG NMI handler category Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 10/21] watchdog/hardlockup: Add function to enable NMI watchdog on all allowed CPUs at once Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 11/21] x86/watchdog/hardlockup: Add an HPET-based hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 12/21] watchdog/hardlockup/hpet: Adjust timer expiration on the number of monitored CPUs Ricardo Neri
2019-06-11 20:11   ` Thomas Gleixner [this message]
2019-06-18 22:46     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 13/21] x86/watchdog/hardlockup/hpet: Determine if HPET timer caused NMI Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 14/21] watchdog/hardlockup: Use parse_option_str() to handle "nmi_watchdog" Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 15/21] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 16/21] x86/watchdog: Add a shim hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 17/21] x86/tsc: Switch to perf-based hardlockup detector if TSC become unstable Ricardo Neri
2019-06-07  0:35   ` Stephane Eranian via iommu
2019-06-07 14:14     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 18/21] x86/apic: Add a parameter for the APIC delivery mode Ricardo Neri
2019-06-16  9:55   ` Thomas Gleixner
2019-06-18 22:47     ` Ricardo Neri
2019-06-18 23:15       ` Thomas Gleixner
2019-05-24  1:16 ` [RFC PATCH v4 19/21] iommu/vt-d: Rework prepare_irte() to support per-irq " Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 20/21] iommu/vt-d: hpet: Reserve an interrupt remampping table entry for watchdog Ricardo Neri
2019-06-16 18:42   ` Thomas Gleixner
2019-06-16 19:21   ` Thomas Gleixner
2019-06-17  8:25     ` Thomas Gleixner
2019-06-17 21:38       ` Stephane Eranian via iommu
2019-06-17 23:08         ` Thomas Gleixner
2019-06-19 15:43           ` Jacob Pan
2019-06-21 15:33             ` Thomas Gleixner
2019-06-21 17:31               ` Jacob Pan
2019-06-21 18:39                 ` Jacob Pan
2019-06-21 20:05                   ` Thomas Gleixner
2019-06-21 23:55                     ` Ricardo Neri
2019-06-22  7:21                       ` Thomas Gleixner
2019-06-18 22:45       ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 21/21] x86/watchdog/hardlockup/hpet: Support interrupt remapping Ricardo Neri
2019-06-16  8:44   ` Thomas Gleixner
2019-06-16  8:53     ` Thomas Gleixner

Reply instructions:

You may reply publically 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=alpine.DEB.2.21.1906112205170.2214@nanos.tec.linutronix.de \
    --to=tglx@linutronix.de \
    --cc=Babu.Moger@amd.com \
    --cc=akpm@linux-foundation.org \
    --cc=andi.kleen@intel.com \
    --cc=ashok.raj@intel.com \
    --cc=ast@kernel.org \
    --cc=bp@suse.de \
    --cc=byungchul.park@lge.com \
    --cc=colin.king@canonical.com \
    --cc=dave@stgolabs.net \
    --cc=dzickus@redhat.com \
    --cc=eranian@google.com \
    --cc=frederic@kernel.org \
    --cc=iommu@lists.linux-foundation.org \
    --cc=jacob.jun.pan@intel.com \
    --cc=jpoimboe@redhat.com \
    --cc=kai.heng.feng@canonical.com \
    --cc=konrad.wilk@oracle.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=longman@redhat.com \
    --cc=marc.zyngier@arm.com \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=mcgrof@kernel.org \
    --cc=mhiramat@kernel.org \
    --cc=mingo@kernel.org \
    --cc=mpe@ellerman.id.au \
    --cc=npiggin@gmail.com \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=peterz@infradead.org \
    --cc=pombredanne@nexb.com \
    --cc=rafael.j.wysocki@intel.com \
    --cc=ravi.v.shankar@intel.com \
    --cc=rdunlap@infradead.org \
    --cc=ricardo.neri-calderon@linux.intel.com \
    --cc=ricardo.neri@intel.com \
    --cc=rientjes@google.com \
    --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

IOMMU Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-iommu/0 linux-iommu/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-iommu linux-iommu/ https://lore.kernel.org/linux-iommu \
		iommu@lists.linux-foundation.org iommu@archiver.kernel.org
	public-inbox-index linux-iommu


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.linux-foundation.lists.iommu


AGPL code for this site: git clone https://public-inbox.org/ public-inbox