[erlang-bugs] otp --with-libatomic_ops compile hangs
Wed Sep 15 20:39:20 CEST 2010
Rickard Green wrote:
>> Feng Yu wrote:
>>> Build Options: --with-libatomic_ops=/usr
>>> Linux yufeng-laptop 2.6.32-25-generic #43-Ubuntu SMP Wed Sep 1
>>> UTC 2010 x86_64 GNU/Linux
>>> apt-get -y install libatomic-ops-dev
>>> Symptom: beam.smp hangs/doesn't terminate
>>> Steps to reproduce:
>>> There are two known ways to reproduce the issue and the simplest is:
>>> $ git clone git://github.com/erlang/otp.git
>>> $ cd otp
>>> $ ./otp_build autoconf
>>> $ ./configure --with-libatomic_ops=/usr
>>> $ make
>>> erlc -W +debug_info +inline -o../ebin hipe_rtl.erl
>>> make hang here.
>> Configuring with libatomic_ops seems to be a new option since
>> post-R14A. Since you're on x86_64 Linux you shouldn't need it.
>> Does it work without that option?
> I was able to reproduce the hang using libatomic_ops-1.2 and
> libatomic_ops-7.2alpha4 on an Ubuntu 9.10, x86_64, gcc 4.4.1. However,
> using the atomic implementation part of OTP every things works fine.
> On SLES 10.1, x86_64, gcc 4.1.2, libatomic_ops-7.2alpha4 worked fine.
> We have added support for use of libatomic_ops since it makes it
> possible to utilize optimized native atomic operations on more platforms
> than before. On x86_64 there is however no need to use libatomic_ops. If
> configure doesn't complain, there is no need for libatomic_ops.
> Cut from release the note:
> The ethread library contains native atomic implementations for, x86
> (32 and 64 bit), powerpc (32 bit), sparc V9 (32 and 64 bit), and
> tilera (32 bit). On other hardware gcc's builtin support for atomic
> memory access will be used if such exists. If no such support is
> found, configure will warn about no atomic implementation available.
> The ethread library can now also use the libatomic_ops library for
> atomic memory accesses. This makes it possible for the Erlang runtime
> system to utilize optimized native atomic operations on more
> platforms than before. If configure warns about no atomic
> implementation available, try using the libatomic_ops library. Use
> the --with-libatomic_ops=PATH configure command line argument when
> specifying where the libatomic_ops installation is located. The
> libatomic_ops library can be downloaded from:
> It looks like a bug outside of OTP, and we currently don't have the time
> to look closer into this, but we will do that when time allows us some
> time in the future.
> Rickard Green
AO_compare_and_swap_full() for x86_64 in libatomic_ops has been reported
I patched AO_compare_and_swap_full() in libatomic_ops-7.2alpha4 with the
corrected version of fix number 2 by Patrick Marlier (see Patrick
Marlier's second mail at the page mentioned above).
After applying the fix, the previously hanging build succeeded. However,
as mentioned earlier, on x86_64 libatomic_ops isn't needed.
Rickard Green, Erlang/OTP, Ericsson AB.
More information about the erlang-bugs