Hi Christoph,

On Wed, Feb 19, 2020 at 12:53 AM Thiede, Christoph <
Christoph.Thiede at student.hpi.uni-potsdam.de> wrote:

> Hi Eliot,
>
>
> > Do you see such distortion on other garbage collections?
>
>
> I could not yet reproduce this during GC.
>
>
> > Can you please check in the VM Stats how long the compaction phase of
> the snapshot GC takes?
>
>
> You mean this:
>

Yes.


> GCs 1,151 (408 ms between GCs 196.6 ms runtime between GCs)
> full 7 totalling 2,729 ms (1.21% runtime), avg 389.9 ms
> marking 1,574 ms (57.7%) avg 224.9 ms,
> compacting 1,155 ms (42.3%) avg 165 ms
>
> The issue is sporadic. Today, I did not yet perceive it again. I can check
> this again directly after the next accident.
>

So if compaction takes on average 0.17 seconds it is unlikely to be the
cause of the distortion.  I wonder how we can debug this.  One way would be
to run the VM from the console under GDB and then interrupt the gdb session
if and when you see the distortion.  You'd have to be watching for it.
Then you could see what the BVM is doing while the distortion is showing,
and check if displayBits et al (the address and dimensions of the bits that
constitute the display) actually agree with the current display object.
Otherwise we're flying blind.

> Best,
>
> Christoph
> <http://www.hpi.de/>
> ------------------------------
> *Von:* Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im
> Auftrag von Eliot Miranda <eliot.miranda at gmail.com>
> *Gesendet:* Mittwoch, 19. Februar 2020 04:06:36
> *An:* The general-purpose Squeak developers list
> *Cc:* Open Smalltalk Virtual Machine Development Discussion
> *Betreff:* Re: [squeak-dev] VM rendering on Windows looks weird after
> saving the image
>
>
>
> On Tue, Feb 18, 2020 at 12:27 AM Thiede, Christoph <
> Christoph.Thiede at student.hpi.uni-potsdam.de> wrote:
>
>> Hi all,
>>
>>
>> some of my images take a very long time to save, despite SSD, often more
>> than 10 seconds. Image file is 700M and changes file 90M. During saving the
>> image, the VM does not react so Windows is diagnosing Squeak might have
>> hung up. It would be nice to show some kind of (VM-side?) progress bar
>> instead ...
>>
>>
>> However, the actual problem is how my host window looks after the saving
>> is complete and the VM comes alive again:
>>
>>
>>
>>
>> I can see this quite often after saving large image files. This state
>> remains for around one second, then I can proceed using the image as usual.
>>
>
> The image is garbage collected and compacted on snapshot, so the display
> may indeed move. However, post garbage collect the location of the display
> is updated, as after a normal full garbage collection.  Do you see such
> distortion on other garbage collections?  Can you please check in the VM
> Stats how long the compaction phase of the snapshot GC takes?  If that is
> as long as you see the distortion then the solution would be to defer
> display updates around at least the compaction phase.
>
>> Best,
>>
>> Christoph
>>
>
> _,,,^..^,,,_
> best, Eliot
>
>

-- 
_,,,^..^,,,_
best, Eliot
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