Patch that "fixes" compositor-x11

[Prigent, Christophe]

Bill,

> Can you find out if my "fix" of printing to a terminal on the same 
> screen also works on your system?

Is this fix integrated?
I recently synchronized and built again. I'm still reproducing the problem of slowness.

Christophe.

-----Original Message-----
From: wayland-devel-bounces+christophe.prigent=intel.com at lists.freedesktop.org [mailto:wayland-devel-bounces+christophe.prigent=intel.com at lists.freedesktop.org] On Behalf Of Ander Conselvan de Oliveira
Sent: Monday, June 11, 2012 10:07 AM
To: Bill Spitzak
Cc: wayland
Subject: Re: Patch that "fixes" compositor-x11

On 06/08/2012 10:26 PM, Bill Spitzak wrote:
> Actually I am running classic with no effects already and I am having 
> this bug.
>
> That explains why nothing happened when I ran ccsm and turned the 
> detector on/off. There was no program to kill/restart.

Ok, so we're dealing with different problems.

> Unless the x11_compositor_handle_event() is the *last* thing called 
> before it does the epoll, I think there could be a problem. If it does 
> a composite afterwards that will do some xcb calls and perhaps make 
> the fd non-ready even though events are ready. However my explanation 
> still requires there to be bugs in xcb as it obviously eventually 
> calls x11_compositor_handle_event and that still only reads one of the 
> events even though it calls xcb_wait.
>
> Can you find out if my "fix" of printing to a terminal on the same 
> screen also works on your system?

I don't have any problems on my system, so running it here wouldn't change anything. Also, I no longer have access to the system with the problem with compiz.

Cheers,
Ander

> Ander Conselvan de Oliveira wrote:
>> On 06/08/2012 09:22 AM, Bill Spitzak wrote:
>>> On 06/07/2012 02:33 AM, Ander Conselvan de Oliveira wrote:
>>>
>>>> I looked at Christophe's machine that has the same problem. He was 
>>>> also running Ubuntu 11.04 on classic mode. It looks like the 
>>>> problem might be in compiz with this particular configuration. When 
>>>> I disabled the "detection" extension on ccsm, compiz restarted and 
>>>> weston started to run fine. The problem returned after a log 
>>>> out/log in cycle. The extension was disable and turning it back on 
>>>> fixed the problem again. So it seems the reset caused by ccsm that 
>>>> actually fixed the issues. Since the problem seems to be in compiz, 
>>>> I stopped debugging.
>>>
>>> I tried a few things called "detection" on ccsm, but none of them 
>>> made compiz restart as far as I can tell, and none of them make any 
>>> difference for me.
>>
>> The extension I disabled dealt with blacklisting know bad drivers or 
>> PCI ids. Christophe's locale is fr_FR, so maybe the name is different 
>> for you.
>>
>>> I suspect there is a problem: xcb_poll can return true even if the 
>>> fd is not ready, because there are events already read into the 
>>> internal queue. However it should read *all* pending events once it 
>>> decides to read one, so it should not produce the slowness, just latency.
>>>
>>> I think compositor-x11 needs to call xcb_poll just before it calls 
>>> epoll with a non-zero timeout. I'm going to check if this fixes it.
>>
>> I don't think that would make any difference. The way the event loop 
>> works, x11_compositor_handle_event() is called even if there is 
>> nothing to read on the fd, exactly because of the internal queue. 
>> This logic is in the libwayland-server (c.f. 
>> wayland/src/event-loop.c). The event source for the xcb connection 
>> should be on the check_list for the post_dispatch_check.
>>
>> Anyway, what drove me to the conclusion that this is compiz related 
>> is the fact that the problem won't happen when running in Ubuntu 
>> Classic mode with no effects. Killing compiz also made the Weston 
>> window responsive again. Christophe also had a cpu/memory/etc 
>> indicator on his panel and it would slow down when moving the pointer 
>> over Weston's window.
>>
>> I won't have access to Christophe's machine again and I can't 
>> reproduce the problem on my machine (even though I'm running Ubuntu 
>> 11.04, it doesn't happen here, not even in Ubuntu Classic mode) so I 
>> can't debug this any further.
>>
>>
>> Cheers,
>> Ander

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