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From: "Yordan Karadzhov (VMware)" <y.karadz@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>,
	"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
Cc: linux-trace-devel@vger.kernel.org
Subject: Re: [PATCH 0/2] KernelShark2.0: Use libtracefs APIs to access tracefs
Date: Mon, 9 Mar 2020 11:17:44 +0200
Message-ID: <4aab233c-6f5b-59a7-564b-e520ed1f569f@gmail.com> (raw)
In-Reply-To: <20200306173411.783cccd0@gandalf.local.home>



On 7.03.20 г. 0:34 ч., Steven Rostedt wrote:
> On Fri, 6 Mar 2020 15:13:56 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
> 
>> On Fri,  6 Mar 2020 11:29:00 +0200
>> "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:
>>
>>> From: "Tzvetomir (VMware)  Stoyanov" <tz.stoyanov@gmail.com>
>>>
>>> The tracefs library provides APIs for accessing files from tracefs.
>>> The library is part of trace-cmd, it is installed as part of trace-cmd
>>> installation. KernelShark uses some of those APIs and must be linked with
>>> the library
>>>
>>> Tzvetomir (VMware)  Stoyanov (2):
>>>    KernelShark2.0: Link KernelShark to libtracefs
>>>    KernelShark2.0: Use libtracefs APIs to access tracefs
>>>    
>>
>> I added these patches to the latest kernelshark-2.0 and it still doesn't
>> work for me. I did a little debugging, and noticed that it fails while
>> reading the guest trace.dat file with:
>>
>> plugin "kvm_combo" failed to initialize on stream /tmp/trace-host-Fedora21.
>>
>> It seems to require that the guest trace.dat file has kvm events?
>>
>> Note, as I build my guest kernel with a make localmodconfig, which disables
>> all modules that are not necessary to boot the box, there is no kvm events
>> there. I can see why the host may need them, but not the guest. I'll
>> rebuild my guest kernel with kvm events and see if that solves this (but
>> that shouldn't be the case).
>>
> 
> Just confirmed it. If I add kvm events to the guest, it synchronizes
> automatically. Thus, it's a bug to expect the guest to have kvm events, as
> there's no reason for them to do so.

Is it possible that something else gets enabled during the recording of 
the data, that actually makes the difference?
Y.

> 
> -- Steve
> 

  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-06  9:29 Tzvetomir Stoyanov (VMware)
2020-03-06  9:29 ` [PATCH 1/2] KernelShark2.0: Link KernelShark to libtracefs Tzvetomir Stoyanov (VMware)
2020-03-06  9:29 ` [PATCH 2/2] KernelShark2.0: Use libtracefs APIs to access tracefs Tzvetomir Stoyanov (VMware)
2020-03-06 20:13 ` [PATCH 0/2] " Steven Rostedt
2020-03-06 22:34   ` Steven Rostedt
2020-03-09  9:17     ` Yordan Karadzhov (VMware) [this message]
2020-03-09 15:44       ` Steven Rostedt
2020-03-09 16:30         ` Steven Rostedt
2020-03-09  9:10   ` Yordan Karadzhov (VMware)

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