From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH 1/3] KVM: trace mmio read event properly
Date: Tue, 17 Jan 2012 10:36:37 +0800 [thread overview]
Message-ID: <4F14DEB5.6020902@linux.vnet.ibm.com> (raw)
In-Reply-To: <4F13F967.5000007@redhat.com>
On 01/16/2012 06:18 PM, Avi Kivity wrote:
> On 01/16/2012 11:31 AM, Xiao Guangrong wrote:
>> In current code, we use KVM_TRACE_MMIO_READ to trace mmio read event which
>> only can be completed immediately, instead of it, we trace the time when
>> read event occur, then cooperate with then later patch, we can know the time
>> of mmio read emulation
>>
>> @@ -3744,6 +3740,8 @@ mmio:
>> /*
>> * Is this MMIO handled locally?
>> */
>> + trace_kvm_mmio(write ? KVM_TRACE_MMIO_WRITE : KVM_TRACE_MMIO_READ,
>
> It's better to push the conditional to the trace event itself, so it's
> only evaluated if tracing is enabled.
>
Yes.
>> + bytes, gpa, *(u64 *)val);
>
> We get the wrong value for reads here, no?
>
Yes, the value is meaningless in this point.
> Can't we leave the code as is, and infer the start of the event from the
> last kvm_exit trace?
Yes, we can do it, but the same problems is we need trace vcpu id to get its
vmexit, i will do it in the next version if you like this way :)
next prev parent reply other threads:[~2012-01-17 2:36 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-16 9:30 [RFC][PATCH] KVM: perf: a smart tool to analyse kvm events Xiao Guangrong
2012-01-16 9:31 ` [PATCH 1/3] KVM: trace mmio read event properly Xiao Guangrong
2012-01-16 10:18 ` Avi Kivity
2012-01-17 2:36 ` Xiao Guangrong [this message]
2012-01-16 9:32 ` [PATCH 2/3] KVM: improve trace events of vmexit/mmio/ioport Xiao Guangrong
2012-01-16 9:38 ` Avi Kivity
2012-01-17 2:28 ` Xiao Guangrong
2012-01-17 11:55 ` Marcelo Tosatti
2012-01-17 17:31 ` David Ahern
2012-01-18 2:32 ` Xiao Guangrong
2012-01-18 5:34 ` David Ahern
2012-01-24 12:44 ` Avi Kivity
2012-01-16 9:32 ` [PATCH 3/3] KVM: perf: kvm events analysis tool Xiao Guangrong
2012-01-16 10:04 ` Avi Kivity
2012-01-17 2:30 ` Xiao Guangrong
2012-01-24 12:49 ` Avi Kivity
2012-01-16 10:08 ` Stefan Hajnoczi
2012-01-17 2:37 ` Xiao Guangrong
2012-01-17 11:59 ` Marcelo Tosatti
2012-01-24 12:51 ` Avi Kivity
2012-01-16 10:11 ` [RFC][PATCH] KVM: perf: a smart tool to analyse kvm events Avi Kivity
2012-01-17 2:30 ` Xiao Guangrong
2012-01-16 22:53 ` David Ahern
2012-01-17 2:41 ` Xiao Guangrong
2012-01-17 4:49 ` David Ahern
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