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From: Yordan Karadzhov <y.karadz@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Linux Trace Devel <linux-trace-devel@vger.kernel.org>
Subject: Re: [PATCH] kernel-shark: Add check for return of ksmodel_get_cpu_front()
Date: Tue, 11 May 2021 16:51:45 +0300	[thread overview]
Message-ID: <be412fdb-3064-6456-9ae7-3739014fdde6@gmail.com> (raw)
In-Reply-To: <20210511094045.1673b76a@gandalf.local.home>



On 11.05.21 г. 16:40, Steven Rostedt wrote:
> On Tue, 11 May 2021 16:25:35 +0300
> Yordan Karadzhov <y.karadz@gmail.com> wrote:
> 
>>> You can reproduce this with:
>>>
>>>      http://rostedt.org/private/trace-no-map.tar.bz2

What should I do to make it SEGFAULT?
Y.

>>>
>>> diff --git a/src/KsPlotTools.cpp b/src/KsPlotTools.cpp
>>> index 225dc34..abef5f8 100644
>>> --- a/src/KsPlotTools.cpp
>>> +++ b/src/KsPlotTools.cpp
>>> @@ -1280,7 +1280,7 @@ void Graph::fillTaskGraph(int sd, int pid)
>>>    						 false,
>>>    						 _collectionPtr,
>>>    						 &index);
>>
>> I wonder why this fails? Is it because "pid" is negative? The fix below
>> is appropriate, however we should detect negative PIDs and abort
>> plotting much earlier.
> 
> I believe the issue is that we failed to map which host task goes with
> which guest vCPUU, and just randomly picked one (or none).
> 
> I fixed trace-cmd to get the mappings when qemu is not found, and
> KernelShark works fine on that case. This bug only appears when it can't
> find the host thread that corresponds to the guest vCPU.
> 
> -- Steve
> 

  reply	other threads:[~2021-05-11 13:51 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-07 13:38 [PATCH] kernel-shark: Add check for return of ksmodel_get_cpu_front() Steven Rostedt
2021-05-11 13:25 ` Yordan Karadzhov
2021-05-11 13:40   ` Steven Rostedt
2021-05-11 13:51     ` Yordan Karadzhov [this message]
2021-05-14 11:50 ` Yordan Karadzhov

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