From: Gleb Natapov <gleb@redhat.com>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Beth Kon <eak@us.ibm.com>,
dlaor@redhat.com, Sheng Yang <sheng@linux.intel.com>,
kvm@vger.kernel.org
Subject: Re: The HPET issue on Linux
Date: Thu, 7 Jan 2010 08:45:28 +0200 [thread overview]
Message-ID: <20100107064528.GR4905@redhat.com> (raw)
In-Reply-To: <4B4511D6.1030401@codemonkey.ws>
On Wed, Jan 06, 2010 at 04:42:30PM -0600, Anthony Liguori wrote:
> On 01/06/2010 02:37 PM, Gleb Natapov wrote:
> >We have exactly that hook in apic already and that's how RTC determines
> >that interrupt was coalesced.
>
> AFAICT, apic_irq_delivered is only reset explicitly by the RTC when
> the line is lowered. It's not currently lowered based on EOI.
>
Correct. We can expose ACK notifiers to userspace (and if we want to
move assigned devices into userspace we have to), but I'd rather avoid
it.
> How can this mechanism be used with the HPET when operating in edge
> triggered mode?
>
If interrupt is coalesced increment counter and double HPET timer
frequency. When counter is zeroed return HPET timer to normal frequency.
--
Gleb.
next prev parent reply other threads:[~2010-01-07 6:45 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-06 9:48 The HPET issue on Linux Sheng Yang
2010-01-06 10:09 ` Gleb Natapov
2010-01-06 10:23 ` Dor Laor
2010-01-06 18:36 ` Beth Kon
2010-01-06 19:20 ` Beth Kon
2010-01-06 19:23 ` Anthony Liguori
2010-01-06 19:44 ` Gleb Natapov
2010-01-06 19:51 ` Anthony Liguori
2010-01-06 20:37 ` Gleb Natapov
2010-01-06 22:42 ` Anthony Liguori
2010-01-07 6:45 ` Gleb Natapov [this message]
2010-01-07 3:01 ` Sheng Yang
2010-02-02 18:13 ` No longer working on HPET Beth Kon
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