LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "Marcin Slusarz" <marcin.slusarz@gmail.com>
Cc: "Ingo Molnar" <mingo@elte.hu>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	"Peter Zijlstra" <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH] documentation: nmi_watchdog=2 works on x86_64 (was: 2.6.25-rc: complete lockup on boot/start of X (bisected))
Date: Sun, 23 Mar 2008 13:15:50 -0700	[thread overview]
Message-ID: <86802c440803231315q2373ec0fp74df1c583ff5695b@mail.gmail.com> (raw)
In-Reply-To: <20080323200625.GB6028@joi>

On Sun, Mar 23, 2008 at 1:06 PM, Marcin Slusarz
<marcin.slusarz@gmail.com> wrote:
> On Sun, Mar 23, 2008 at 08:06:08PM +0100, Peter Zijlstra wrote:
>  > On Sun, 2008-03-23 at 19:46 +0100, Marcin Slusarz wrote:
>  >
>  > > 4 different lockups:
>  > > http://alan.umcs.lublin.pl/~mslusarz/kernel/2008.03.23-lockup/
>  >
>  > Brilliant, these are extremely helpful.
>  >
>  > What seems to happen is a classic xtime deadlock, doing a xtime
>  > seq_readlock while holding a seq_writelock.
>  >
>  > Only need to figure out _why_ that is happening....
>  >
>  > > Are there any downsides of using nmi_watchdog=2 all the time?
>  >
>  > Some machines are said to not boot due to NMIs, hence the default is
>  > off, but afaik, _if_ it works there are no downsides aside from the
>  > slight NMI handling overhead.
>  >
>  > > ps: Documentation/nmi_watchdog.txt says: "Currently, local APIC mode
>  > > (nmi_watchdog=2) does not work on x86-64.". It's not true, so maybe someone
>  > > should update this file?
>  >
>  > Care to send a patch to the x86 maintainers? :-)
>  >
>
>  ---
>  documentation: nmi_watchdog=2 works on x86_64
>
>  Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
>  Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
>  ---
>   Documentation/nmi_watchdog.txt |    3 +--
>   1 files changed, 1 insertions(+), 2 deletions(-)
>
>  diff --git a/Documentation/nmi_watchdog.txt b/Documentation/nmi_watchdog.txt
>  index c025a45..757c729 100644
>  --- a/Documentation/nmi_watchdog.txt
>  +++ b/Documentation/nmi_watchdog.txt
>  @@ -23,8 +23,7 @@ kernel debugging options, such as Kernel Stack Meter or Kernel Tracer,
>   may implicitly disable the NMI watchdog.]
>
>   For x86-64, the needed APIC is always compiled in, and the NMI watchdog is
>  -always enabled with I/O-APIC mode (nmi_watchdog=1). Currently, local APIC
>  -mode (nmi_watchdog=2) does not work on x86-64.
>  +always enabled with I/O-APIC mode (nmi_watchdog=1).
>
>   Using local APIC (nmi_watchdog=2) needs the first performance register, so
>   you can't use it for other purposes (such as high precision performance
>  --
anyone has nmi_watchdog=1 works on x86_64 with amd platform?

or nmi_watchdog=1 only works with intel box?

maybe we can default that to different value according to different
cpu vendor...

YH

  reply	other threads:[~2008-03-23 20:16 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-02 19:00 2.6.25-rc: complete lockup on boot/start of X (bisected) Marcin Slusarz
2008-03-02 19:11 ` Peter Zijlstra
2008-03-02 19:47   ` Marcin Slusarz
2008-03-02 19:58     ` Peter Zijlstra
2008-03-23 15:44       ` Marcin Slusarz
2008-03-23 15:54         ` Peter Zijlstra
2008-03-23 18:46           ` Marcin Slusarz
2008-03-23 19:06             ` Peter Zijlstra
2008-03-23 19:09               ` Peter Zijlstra
2008-03-23 19:57                 ` Marcin Slusarz
2008-03-23 20:06               ` [PATCH] documentation: nmi_watchdog=2 works on x86_64 (was: 2.6.25-rc: complete lockup on boot/start of X (bisected)) Marcin Slusarz
2008-03-23 20:15                 ` Yinghai Lu [this message]
2008-03-27  9:51                 ` Ingo Molnar
2008-03-02 20:00 ` 2.6.25-rc: complete lockup on boot/start of X (bisected) Arjan van de Ven
2008-03-02 20:08   ` Marcin Slusarz

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=86802c440803231315q2373ec0fp74df1c583ff5695b@mail.gmail.com \
    --to=yhlu.kernel@gmail.com \
    --cc=a.p.zijlstra@chello.nl \
    --cc=linux-kernel@vger.kernel.org \
    --cc=marcin.slusarz@gmail.com \
    --cc=mingo@elte.hu \
    --cc=tglx@linutronix.de \
    --subject='Re: [PATCH] documentation: nmi_watchdog=2 works on x86_64 (was: 2.6.25-rc: complete lockup on boot/start of X (bisected))' \
    /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

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).