From: Avi Kivity <avi@redhat.com>
To: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Sheng Yang <sheng@linux.intel.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Marcelo Tosatti <mtosatti@redhat.com>,
oerg Roedel <joro@8bytes.org>,
Jes Sorensen <Jes.Sorensen@redhat.com>,
Gleb Natapov <gleb@redhat.com>,
Zachary Amsden <zamsden@redhat.com>,
zhiteng.huang@intel.com, tim.c.chen@intel.com,
Arnaldo Carvalho de Melo <acme@infradead.org>
Subject: Re: [PATCH V3] perf & kvm: Enhance perf to collect KVM guest os statistics from host side
Date: Thu, 15 Apr 2010 11:05:33 +0300 [thread overview]
Message-ID: <4BC6C8CD.1020801@redhat.com> (raw)
In-Reply-To: <1902445479.2078.458.camel@ymzhang.sh.intel.com>
On 04/15/2030 04:04 AM, Zhang, Yanmin wrote:
>
>> An even more accurate way to determine this is to check whether the
>> interrupt frame points back at the 'int $2' instruction. However we
>> plan to switch to a self-IPI method to inject the NMI, and I'm not sure
>> wether APIC NMIs are accepted on an instruction boundary or whether
>> there's some latency involved.
>>
> Yes. But the frame pointer checking seems a little complicated.
>
An even bigger disadvantage is that it won't work with Sheng's patch,
self-NMIs are not synchronous.
>>> trace_kvm_entry(vcpu->vcpu_id);
>>> +
>>> + percpu_write(current_vcpu, vcpu);
>>> kvm_x86_ops->run(vcpu);
>>> + percpu_write(current_vcpu, NULL);
>>>
>>>
>> If you move this around the 'int $2' instructions you will close the
>> race, as a stray NMI won't catch us updating the rip cache. But that
>> depends on whether self-IPI is accepted on the next instruction or not.
>>
> Right. The kernel part has dependency on the self-IPI implementation.
> I will move above percpu_write(current_vcpu, vcpu) (or a new wrapper function)
> just around 'int $2'.
>
>
Or create a new function to inject the interrupt in x86.c. That will
reduce duplication between svm.c and vmx.c.
> Sheng would find a solution on the self-IPI delivery. Let's separate my patch
> and self-IPI as 2 issues as we don't know when the self-IPI delivery would be
> resolved.
>
Sure.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2010-04-15 8:06 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2030-04-14 9:05 [PATCH V3] perf & kvm: Enhance perf to collect KVM guest os statistics from host side Zhang, Yanmin
2010-04-14 9:20 ` Avi Kivity
2010-04-14 9:43 ` Sheng Yang
2010-04-14 9:57 ` Avi Kivity
2010-04-14 10:14 ` Sheng Yang
2010-04-14 10:19 ` Avi Kivity
2010-04-14 10:27 ` Sheng Yang
2010-04-14 10:33 ` Avi Kivity
2010-04-14 10:36 ` Sheng Yang
2010-04-14 10:43 ` Ingo Molnar
2010-04-14 11:17 ` Avi Kivity
2030-04-15 1:04 ` Zhang, Yanmin
2010-04-15 8:05 ` Avi Kivity [this message]
2030-04-15 8:57 ` Zhang, Yanmin
2010-04-15 9:04 ` oerg Roedel
2010-04-15 9:09 ` Avi Kivity
2010-04-15 9:44 ` oerg Roedel
2010-04-15 9:48 ` Avi Kivity
2010-04-15 10:40 ` Joerg Roedel
2010-04-15 10:44 ` Avi Kivity
2010-04-15 14:08 ` Sheng Yang
2010-04-17 18:12 ` Avi Kivity
2010-04-19 8:25 ` Avi Kivity
2010-04-20 3:32 ` Sheng Yang
2010-04-20 9:38 ` Avi Kivity
2010-04-27 19:03 ` [PATCH] Psychovisually-optimized HZ setting (2.6.33.3) Uwaysi Bin Kareem
2010-04-27 19:51 ` Randy Dunlap
2010-04-27 21:50 ` Valdis.Kletnieks
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