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From: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	X86 <x86@kernel.org>, Avi Kivity <avi@redhat.com>,
	Jeremy Fitzhardinge <jeremy@goop.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Greg Kroah-Hartman <gregkh@suse.de>,
	Alexander Graf <agraf@suse.de>,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	Gleb Natapov <gleb@redhat.com>,
	Randy Dunlap <rdunlap@xenotime.net>,
	linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	KVM <kvm@vger.kernel.org>,
	Virtualization <virtualization@lists.linux-foundation.org>,
	Xen <xen-devel@lists.xensource.com>,
	Sasha Levin <levinsasha928@gmail.com>,
	Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Subject: Re: [PATCH RFC V5 2/6] kvm hypervisor : Add a hypercall to KVM hypervisor to support pv-ticketlocks
Date: Tue, 17 Apr 2012 12:36:51 +0530	[thread overview]
Message-ID: <4F8D168B.7090806@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120412002909.GD32051@amt.cnet>

On 04/12/2012 05:59 AM, Marcelo Tosatti wrote:
> On Wed, Apr 11, 2012 at 09:06:29PM -0300, Marcelo Tosatti wrote:
>> On Fri, Mar 23, 2012 at 01:37:04PM +0530, Raghavendra K T wrote:
>>> From: Srivatsa Vaddagiri<vatsa@linux.vnet.ibm.com>
>>>
[...]

		barrier();
>>
>> Is it always OK to erase the notification, even in case an unrelated
>> event such as interrupt was the source of wakeup?
>
> Note i am only asking whether it is OK to lose a notification, not
> requesting a change to atomic test-and-clear.

Yes.. got your point.
IMO, this is the only (safe) place where it can clear
kicked(pv_unhalted) flag. Since it is going to be runnable.

and you are also right in having concern on unwanted clear of flag
since that would result in vcpu /vm hangs eventually.

Hope I did not miss anything.

>
> It would be nice to have a comment explaining it.
>

Sure will do that

>>


WARNING: multiple messages have this Message-ID (diff)
From: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
	Greg Kroah-Hartman <gregkh@suse.de>, KVM <kvm@vger.kernel.org>,
	Gleb Natapov <gleb@redhat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	X86 <x86@kernel.org>,
	linux-doc@vger.kernel.org, Alexander Graf <agraf@suse.de>,
	LKML <linux-kernel@vger.kernel.org>,
	Randy Dunlap <rdunlap@xenotime.net>,
	Ingo Molnar <mingo@redhat.com>,
	Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
	Avi Kivity <avi@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Virtualization <virtualization@lists.linux-foundation.org>,
	Xen <xen-devel@lists.xensource.com>,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	Sasha Levin <levinsasha928@gmail.com>
Subject: Re: [PATCH RFC V5 2/6] kvm hypervisor : Add a hypercall to KVM hypervisor to support pv-ticketlocks
Date: Tue, 17 Apr 2012 12:36:51 +0530	[thread overview]
Message-ID: <4F8D168B.7090806@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120412002909.GD32051@amt.cnet>

On 04/12/2012 05:59 AM, Marcelo Tosatti wrote:
> On Wed, Apr 11, 2012 at 09:06:29PM -0300, Marcelo Tosatti wrote:
>> On Fri, Mar 23, 2012 at 01:37:04PM +0530, Raghavendra K T wrote:
>>> From: Srivatsa Vaddagiri<vatsa@linux.vnet.ibm.com>
>>>
[...]

		barrier();
>>
>> Is it always OK to erase the notification, even in case an unrelated
>> event such as interrupt was the source of wakeup?
>
> Note i am only asking whether it is OK to lose a notification, not
> requesting a change to atomic test-and-clear.

Yes.. got your point.
IMO, this is the only (safe) place where it can clear
kicked(pv_unhalted) flag. Since it is going to be runnable.

and you are also right in having concern on unwanted clear of flag
since that would result in vcpu /vm hangs eventually.

Hope I did not miss anything.

>
> It would be nice to have a comment explaining it.
>

Sure will do that

>>

  parent reply	other threads:[~2012-04-17  7:22 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-23  8:05 [PATCH RFC V5 0/6] kvm : Paravirt-spinlock support for KVM guests Raghavendra K T
2012-03-23  8:05 ` Raghavendra K T
2012-03-23  8:06 ` [PATCH RFC V5 1/6] debugfs: Add support to print u32 array in debugfs Raghavendra K T
2012-03-23  8:06   ` Raghavendra K T
2012-03-30 20:49   ` [Xen-devel] " Konrad Rzeszutek Wilk
2012-03-30 20:49     ` Konrad Rzeszutek Wilk
2012-03-30 21:11     ` Greg KH
2012-03-30 21:11     ` Greg KH
2012-03-23  8:07 ` [PATCH RFC V5 2/6] kvm hypervisor : Add a hypercall to KVM hypervisor to support pv-ticketlocks Raghavendra K T
2012-03-23  8:07   ` Raghavendra K T
2012-04-12  0:06   ` Marcelo Tosatti
2012-04-12  0:06     ` Marcelo Tosatti
2012-04-12  0:29     ` Marcelo Tosatti
2012-04-12  0:29       ` Marcelo Tosatti
2012-04-17  7:06       ` Raghavendra K T
2012-04-17  7:06       ` Raghavendra K T [this message]
2012-04-17  7:06         ` Raghavendra K T
2012-04-17  3:49     ` Raghavendra K T
2012-04-17  3:49     ` Raghavendra K T
2012-03-23  8:07 ` [PATCH RFC V5 3/6] kvm : Add unhalt msr to aid (live) migration Raghavendra K T
2012-03-23  8:07   ` Raghavendra K T
2012-04-12  0:15   ` Marcelo Tosatti
2012-04-12  0:15     ` Marcelo Tosatti
2012-04-17  7:17     ` Raghavendra K T
2012-04-17  7:17     ` Raghavendra K T
2012-03-23  8:08 ` [PATCH RFC V5 4/6] kvm guest : Added configuration support to enable debug information for KVM Guests Raghavendra K T
2012-03-23  8:08   ` Raghavendra K T
2012-03-23  8:08 ` [PATCH RFC V5 5/6] kvm : pv-ticketlocks support for linux guests running on KVM hypervisor Raghavendra K T
2012-03-23  8:08   ` Raghavendra K T
2012-03-23  8:08 ` [PATCH RFC V5 6/6] Documentation/kvm : Add documentation on Hypercalls and features used for PV spinlock Raghavendra K T
2012-03-23  8:08   ` Raghavendra K T
2012-03-28 18:32 ` [PATCH RFC V5 0/6] kvm : Paravirt-spinlock support for KVM guests Raghavendra K T
2012-03-28 18:32   ` Raghavendra K T
2012-04-12  0:26   ` Marcelo Tosatti
2012-04-12  0:26     ` Marcelo Tosatti

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