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From: Anthony Liguori <anthony@codemonkey.ws>
To: Beth Kon <eak@us.ibm.com>
Cc: dlaor@redhat.com, Gleb Natapov <gleb@redhat.com>,
	Sheng Yang <sheng@linux.intel.com>,
	kvm@vger.kernel.org
Subject: Re: The HPET issue on Linux
Date: Wed, 06 Jan 2010 13:23:28 -0600	[thread overview]
Message-ID: <4B44E330.4080805@codemonkey.ws> (raw)
In-Reply-To: <4B44E27F.6090406@us.ibm.com>

On 01/06/2010 01:20 PM, Beth Kon wrote:
> Beth Kon wrote:
>> I will try to look into this. Since HPET is edge-triggered, looks 
>> like this problem is of a different nature than PIT.  Is this a solid 
>> failure or intermittent?
> Anthony just explained that on x86, even edge-triggered interrupts are 
> queued in the apic and an eoi will occur, so this is not different 
> than the PIT.

Not quite queued in the sense that multiple events will be delivered in 
order, but I think the point is that you can still detect whether 
delivery succeeded by counting APIC EOIs.

The trouble is that historically we've struggled with doing this in 
userspace.  Maybe it's time to revisit.

Regards,

Anthony Liguori

  reply	other threads:[~2010-01-06 19:23 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 [this message]
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
2010-01-07  3:01       ` Sheng Yang
2010-02-02 18:13   ` No longer working on HPET Beth Kon

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