Re: Kernelshark v2 all-black plots area

From: Dario Faggioli <dfaggioli@suse.com>
To: "Yordan Karadzhov (VMware)" <y.karadz@gmail.com>,
	Linux Trace Devel <linux-trace-devel@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Subject: Re: Kernelshark v2 all-black plots area
Date: Wed, 10 Feb 2021 17:15:14 +0100	[thread overview]
Message-ID: <d8e65d2c5c9f225a7cb811535449656e00aa0f1a.camel@suse.com> (raw)
In-Reply-To: <60fd40d8-23ab-6518-4e8b-6d66bbd53f5a@gmail.com>

[-- Attachment #1: Type: text/plain, Size: 2202 bytes --]

On Wed, 2021-02-10 at 17:47 +0200, Yordan Karadzhov (VMware) wrote:
> On 10.02.21 г. 16:51 ч., Dario Faggioli wrote:
> > Then, I append the trace-(null).dat file (the guest trace). I do
> > see
> > this on the terminal:
> 
> I see what you mean. In this case the host and the guest are not 
> synchronized at all. I guess something went wrong during the
> recording. 
> Also the fact that the name of the guest VM is "(null)" looks very 
> suspicious. I guess this is not the real name of the VM you are
> using?
> 
Well, it is weird, but I think Tzvetomir figured it out. Or at least,
it's probably an issue while parsing the qemu command line for trying
to figure out the name of the guest.

It's indeed strange and annoying, but I don't think it necessarily
means the trace is not valid.

Also, it sure can be something like that. But if I just open the guest
trace alone (or I check the records with `trace-cmd report`), it seems
fine and the timestamps are not crazy.

The screenshot of me doing that is this one:

http://xenbits.xen.org/people/dariof/ks2-debug/kernelshark-v2-guest.png

> Steven, do you have any idea what can cause such problem?
> 
The trace is here:

http://xenbits.xen.org/people/dariof/ks2-debug/trace-(null).dat

With `trace-cmd dump --options`, I see this:

 sudo trace-cmd dump --options trace-\(null\).dat 
		[Option TRACECLOCK, 0 bytes]
		[Option UNAME, 47 bytes]
Linux tumbleweed-jeos 5.10.12-1-default x86_64
		[Option VERSION, 47 bytes]
2.9.1 1b6bba6c0682975377477d5eabfd541c060aea03
		[Option TRACEID, 8 bytes]
0xD663C16F20E1B52E
		[Option TimeShift, 68 bytes]
0xD8F36FC634D63137 [peer's trace id]
0x0 [peer's protocol flags]
0x1 [peer's CPU count]
2 [samples count for CPU 0]
	71075647069541 281474976710656 8311226241638 [offset * scaling @ time]
	71075647069541 281474976710656 8315062444376 [offset * scaling @ time]

Thanks and Regards
-- 
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
-------------------------------------------------------------------
<<This happens because _I_ choose it to happen!>> (Raistlin Majere)

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 833 bytes --]