[Gc] Boehm GC and Iphone

Damian damian.pop at gmail.com
Mon Jan 17 22:24:33 PST 2011


Hi Ivan, thanks for helping me with this.
1. I defined none of those, should I define any? (I tried both after I read
this but I get the same exception)
2. My app only runs on iphone, but I tried it in the iphone simulator and it
does not crash. I builded the gc just like for the simulator but for x86
arch and it seems to work.
3. How? How do I build the collector with symbols on? I tried adding -g to
compiler options and I get a library more than twice bigger so I thing it
has the symbols, but when debugging the stack is the same.

Thanks again!
Damian

2011/1/17 Ivan Maidanski <ivmai at mail.ru>

> Hi Damian,
>
> 1. Is the mode is GC_DISCOVER_TASK_THREADS or GC_NO_THREADS_DISCOVERY?
> 2. Could you try your app on Mac OS X?
> 3. Could you debug with symbols on and tell us the reason of abort call?
> 4. GC_get_parallel() returns non-zero if 2 or more markers are running.
> 5. Incremental/generation mode is turned on only if either
> GC_enable_incremental() is called (unless GC_DISABLE_INCREMENTAL env var is
> set) or GC_ENABLE_INCREMENTAL env var is set.
>
> Regards.
>
> Sun, 16 Jan 2011 01:18:05 -0300 Damian <damian.pop at gmail.com>:
>
> > Well, I was not calling gc_enable_incremental() so I think it was not
> > enabled.
> > Now I added the call but the program execution is aborted with this stack
> > trace:
> >
> > #0  0x31cbcffc in __abort ()
> >
> > #1  0x31cbd04c in abort ()
> >
> > #2  0x31c91fcc in internal_catch_exception_raise ()
> >
> > #3  0x31c81ea4 in _Xexception_raise ()
> >
> > #4  0x31c81ab0 in exc_server ()
> >
> > #5  0x00060f20 in GC_mprotect_thread ()
> >
> > #6  0x31caa284 in _pthread_start ()
> >
> > #7  0x31c9f2b0 in thread_start ()
> >
> >
> > Any help?
> > Thanks!
> >
> >
> > On Sat, Jan 15, 2011 at 8:14 PM, Damian <damian.pop at gmail.com> wrote:
> >
> > > Hi, I've just built gc7.2 BDWGC for iphone device, and it's working.
> > > How can I make sure that generation mode is on and working?
> > > And, parallel mark doesn't work on single core cpus?
> > >
> > > Damian.
> > >
> > > 2011/1/13 Ivan Maidanski <ivmai at mail.ru>
> > >
> > >> Hi,
> > >>
> > >> If the platform is not multi-core then parallel-mark mode should be
> off
> > >> (either at compile time or at runtime).
> > >> But turning on generation mode could reduce the GC pause on a
> single-core.
> > >>
> > >> Regards.
> > >>
> > >> Thu, 13 Jan 2011 08:28:55 -0300 Damian <damian.pop at gmail.com>:
> > >> > None is multicore. Will I get an inprovement anyway?
> > >> > Ok, I will try to compile gc7.2 BDWGC snapshot tonight.
> > >> > Thanks!
> > >> >
> > >> > 2011/1/13 Ivan Maidanski <ivmai at mail.ru>
> > >> >
> > >> > > Hi,
> > >> > >
> > >> > > 1. Are you going to run it on a multi-core? (I don't know Apples
> > >> devices
> > >> > > internals deeply, so I wonder which of them have multi-core CPUs).
> > >> > >
> > >> > > 2. If you start using gc6.8 just because of the reason you
> mentioned,
> > >> I
> > >> > > recommend you to migrate to gc7.2 (get the recent BDWGC snapshot
> which
> > >> now
> > >> > > has generation plus parallel collection enabled).
> > >> > >
> > >> > > 3. Incremental/generation collection as well as parallel marking
> are
> > >> the GC
> > >> > > improvements aiming collection pause reduction.
> > >> > >
> > >> > > Regards.
> > >> > >
> > >> > > Wed, 12 Jan 2011 20:03:02 -0300 Damian <damian.pop at gmail.com>:
> > >> > >
> > >> > > > Maybe concurrent + parallel collection does not what I'm
> expecting.
> > >> > > > What I need to achieve is to reduce the collection pause.
> > >> > > > I'm using version 6.8 (because I've found somewhere on the
> internet
> > >> > > someone
> > >> > > > has made it work on iphone with some changes) and I'm having
> > >> collection
> > >> > > > cycles of about 120ms. I need to reduce that number. I don't
> care if
> > >> > > overall
> > >> > > > collection time increases as long as the app is not freezed for
> such
> > >> a
> > >> > > long
> > >> > > > time.
> > >> > > > Is that possible?
> > >> > > >
> > >> > > > Thanks.
> > >> > > >
> > >> > > > 2011/1/12 Ivan Maidanski <ivmai at mail.ru>
> > >> > > >
> > >> > > > > Hi,
> > >> > > > >
> > >> > > > > BTW What Apple devices has a multi-core CPU at present?
> > >> > > > >
> > >> > > > > I ran GC test on a single-core with GC_MARKERS=4 - collector
> > >> appears to
> > >> > > > > work...
> > >> > > > >
> > >> > > > > Wed, 12 Jan 2011 10:04:00 -0300 Damian <damian.pop at gmail.com
> >:
> > >> > > > >
> > >> > > > > > Hi,
> > >> > > > > > Is it possible to compile boehm gc for iphone enabling
> > >> generational
> > >> > > and
> > >> > > > > parallel collection?
> > >> > > > >
> > >> > > > > See the recent post by Hans.
> > >> > > > >
> > >> > > > > I try to enable generational collection on multi-cores
> (regardless
> > >> > > whether
> > >> > > > > this slows down the GC in average or not - anyway it is not on
> by
> > >> > > default).
> > >> > > > > FYI: At present, generational collection on multi-cores
> enabled
> > >> only on
> > >> > > > > Win32.
> > >> > > > >
> > >> > > > > Regards.
> > >> > > > >
> > >> > > > > > I will try to do so; probably I will need help, but for now
> al
> > >> least
> > >> > > I
> > >> > > > > want to know it it's possible at all.
> > >> > > > > > Thanks
>
>
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