FreeLists / openbeos / [openbeos] Re: openbeos Digest V6 #213

["Axel Dörfler" <axeld@xxxxxxxxxxxxxxxx>]

Hi Ithamar,

"Ithamar Adema" <iradema@xxxxxxxxx> wrote:
> >There currently are 2 major stability problems in Haiku:
> >1) the reference counting with vm_cache/vm_area isn't safe - I 
> > haven't
> >search for the actual error yet, but it sometimes crashes with a
> >debugger message that suggests this is the case
> >2) the VM does not have a page scanner (the one we have is broken 
> > and I
> >disabled it); it never chooses any page to be dispensable.
> I just did a build of Haiku, and tried copying the content of the
> image file from within Haiku to a real partition (using QEMU). This
> failed (crashes in VM) until I increased the memory allocated to 
> Haiku
> in QEMU.

Does it crash because its out of free pages? :-)
Anyway, the sudden reboots can also be reproduced by opening all apps 
at once, several times if it has to. Or using the method Urias 
reported. I also got there after having killed all teams and trying to 
enter the kernel debugger via F12.

> I presume this is a valid test case of the problems your describing?
> If so, I'll start looking into the VM to see if I can help you fix
> this :D

What we need is a page scanner that selects (when memory is getting low 
or shortly before) pages that be freed, that is, pages that weren't in 
use often, and haven't been used for quite some time. A simple two-hand 
clock algorithm with an LRU list should be okay for now.
I wanted to have a look at the current Solaris implementation before 
actually laying out the details, though, but that's not a requirement :
-)
Thanks!

> It would simply be great to have Haiku stable enough to be able to,
> once the basics of the network stack are finished, do development 
> from
> within Haiku itself....

Definitely, I just decided to work on networking first, and then fix 
those stability problems :-)

Bye,
   Axel.