From: Andi Kleen <andi@firstfloor.org>
To: David Miller <davem@davemloft.net>
Cc: andi@firstfloor.org, linux-kernel@vger.kernel.org
Subject: Re: x86's nmi_hz wrt. oprofile's nmi_timer_int.c
Date: Mon, 23 Feb 2009 05:52:00 +0100 [thread overview]
Message-ID: <20090223045159.GR26292@one.firstfloor.org> (raw)
In-Reply-To: <20090222.201152.169082487.davem@davemloft.net>
> Again, the code in nmi_timer_int.c doesn't.
>
> It uses the NMI watchdog timer interrupts, it catches DIE_NMI
> events.
>
> > Does that answer your question?
>
> Not really.
Ah see what you mean now. The nmi_timer_int code can only
be active ever when the cpu is not known to nmi_int.c and
when the nmi watchdog is in io apic mode. But IO apic mode
doesn't use the fast check/slowdown because it always runs
at HZ frequency. That only happens in LAPIC mode.
The standard fallback mode for unknown CPU is the non NMI timer
fallback in oprofile_init, the IO APIC mode happens near never in practice.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2009-02-23 4:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-29 23:58 x86's nmi_hz wrt. oprofile's nmi_timer_int.c David Miller
2009-01-30 15:01 ` Ingo Molnar
2009-01-30 21:54 ` David Miller
2009-02-02 23:14 ` David Miller
2009-02-03 12:27 ` Ingo Molnar
2009-02-22 17:06 ` Andi Kleen
2009-02-23 4:11 ` David Miller
2009-02-23 4:52 ` Andi Kleen [this message]
2009-02-23 5:59 ` David Miller
2009-02-23 6:34 ` Andi Kleen
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