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From: Igor Mammedov <imammedo@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
	x86@kernel.org, jacob.jun.pan@linux.intel.com,
	alan@linux.intel.com, feng.tang@intel.com,
	konrad.wilk@oracle.com, avi@redhat.com, glommer@redhat.com,
	johnstul@us.ibm.com, riel@redhat.com, tj@kernel.org,
	kosaki.motohiro@jp.fujitsu.com, akpm@linux-foundation.org,
	amit.shah@redhat.com
Subject: Re: [PATCH RFC] pvclock: Make pv_clock more robust and fixup it if overflow happens
Date: Mon, 13 Feb 2012 19:15:07 +0100	[thread overview]
Message-ID: <4F39532B.3060203@redhat.com> (raw)
In-Reply-To: <20120213174837.GA11513@amt.cnet>

On 02/13/2012 06:48 PM, Marcelo Tosatti wrote:
> On Mon, Feb 13, 2012 at 04:45:59PM +0100, Igor Mammedov wrote:
>> Instead of hunting misterious stalls/hungs all over the kernel when
>> overflow occurs at pvclock.c:pvclock_get_nsec_offset
>>
>>      u64 delta = native_read_tsc() - shadow->tsc_timestamp;
>>
>> and introducing hooks when places of unexpected access found, pv_clock
>> should be initialized for the calling cpu if overflow condition is detected.
>>
>> Signed-off-by: Igor Mammedov<imammedo@redhat.com>
>
> Igor,
>
> I disagree. This is fixing the symptom not the root cause. Additionally,
> Xen also uses pvclock_clocksource_read.
>
> How about adding a BUG_ON to detect the overflow, this way hunting for
> the problem is not necessary.
>
Ok, I'll repost bug_on version.

  reply	other threads:[~2012-02-13 18:15 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-07 21:05 x86: kvmclock: abstract save/restore sched_clock_state Marcelo Tosatti
2012-02-08 10:53 ` Igor Mammedov
2012-02-09 12:27 ` Amit Shah
2012-02-09 15:13   ` Igor Mammedov
2012-02-10 10:02     ` Amit Shah
2012-02-10 10:11       ` Igor Mammedov
2012-02-10 10:23         ` Amit Shah
2012-02-10 12:32       ` Marcelo Tosatti
2012-02-10 12:33         ` Marcelo Tosatti
2012-02-10 12:43           ` Igor Mammedov
2012-02-13 12:46             ` Amit Shah
2012-02-13 12:56           ` Amit Shah
2012-02-10 13:18         ` Amit Shah
2012-02-10 20:58           ` Igor Mammedov
2012-02-13 12:39             ` Amit Shah
2012-02-13 13:07 ` x86: kvmclock: abstract save/restore sched_clock_state (v2) Marcelo Tosatti
2012-02-13 15:20   ` Igor Mammedov
2012-02-13 15:52     ` Marcelo Tosatti
2012-02-15 10:28       ` Avi Kivity
2012-02-13 15:45   ` [PATCH RFC] pvclock: Make pv_clock more robust and fixup it if overflow happens Igor Mammedov
2012-02-13 17:48     ` Marcelo Tosatti
2012-02-13 18:15       ` Igor Mammedov [this message]
2012-02-13 16:26   ` x86: kvmclock: abstract save/restore sched_clock_state (v2) Amit Shah
2012-03-01  9:58 ` x86: kvmclock: abstract save/restore sched_clock_state Thomas Gleixner

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