Re: Help with solving a thread safety issue

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Hello, 
I've done  differents tests, with the differents combinaisons between qemu X and spice-server, 
I can say  that is  since video adaptative streaming, the video streaming is bad compare to the  old version (spice 0.12.3 / qemu 1.7 ). 
When i set SPICE_DISABLE_ADAPTIVE_STREAMING=Y , my tests shows that's a lot of frames are dropping, because of sound synchronisation, The only way to get good streaming performance is to desactivate audio from client side. ( --spice-disable-audio).

An other point, when you disable streaming detection from server side, video is good, but the sound is very bad.

Regards, 
Nicolas




2014-09-08 16:57 GMT+02:00 Jeremy White <jwhite@xxxxxxxxxxxxxxx>:
On Sat, Sep 06, 2014 at 08:59:47AM -0500, Jeremy White wrote:
I think there actually is the same issue when running within QEMU: sound
is emitted from a QEMU thread:

Is there a bug or someone that is working on that issue?  I'd be curious to
see if my patch resolves the problem for them.

I've only noticed this through code inspection/gdb breakpoints after you
pointed out the issue you found.  However, I'm fairly sure there has
been reports on this mailing list of sound stopping after a while when
watching a video. This matches very closely what you described.

I was thinking of
http://lists.freedesktop.org/archives/spice-devel/2014-July/017132.html
Maybe there was another email.

I couldn't quickly figure out the threading arrangement in qemu, but if the main channel is being driven by a different thread than the audio channel, then I think this patch would have introduced a bug:

---
commit bf9e210b21a66210b19f69fcaa4542b393b7dc22
Author: Yonit Halperin <yhalperi@xxxxxxxxxx>
Date:   Fri Jan 25 09:34:19 2013 -0500

    red_worker: video streams - adjust client playback latency

--

Of course, that's 18 months ago, so it seems to me we would have found it by now (despite it being a subtle, unpredictable bug that only occurs during video playback).

But, just to be sure, Nicolas, would you mind setting the SPICE_DISABLE_ADAPTIVE_STREAMING environment variable prior to running the client and seeing if that changes anything?

Cheers,

Jeremy

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