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Message-Id: <20081217164243.a7710ae3.ytakahashi@miraclelinux.com>
Date: Wed, 17 Dec 2008 16:42:43 +0900
From: Yoshihiro Takahashi <ytakahashi@...aclelinux.com>
To: Ingo Molnar <mingo@...e.hu>
Cc: linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Eduardo Habkost <ehabkost@...hat.com>,
Huang Ying <ying.huang@...el.com>, kexec@...ts.infradead.org,
Bernhard Walle <bwalle@...e.de>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: kdump hangs up by Sysrq+C trigger in high load.
Ingo. Thank you, your reply.
I will serch it again.
On Tue, 16 Dec 2008 12:09:49 +0100
Ingo Molnar <mingo@...e.hu> wrote:
>
> * Yoshihiro Takahashi <ytakahashi@...aclelinux.com> wrote:
>
> > Hi.
> >
> > kdump hangs up by Sysrq+C trigger once in about 10 times in high load.
> > After the above occurs, kdump cannot collect vmcores with NMI button.
> > When waiting_for_crash_ipi does case more than 0, mdelay seem to make a
> > stall.
> >
> > While nmi_shootdown_cpus(), mdelay may not work since interruption is
> > disable. (ex. when crashing kernel by NMI interruption, all
> > interruption may be disabled.).
> >
> > So I think that it should use other way (TSC) instead of mdelay() in
> > nmi_shootdown_cpus().
>
> mdelay uses either the tsc or CPU loops - neither stop while IRQs are
> disabled.
>
> Could you figure out exactly why it hangs in your case?
>
> Ingo
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