Re: [libunwind] backtrace on EM64T

[David Mosberger-Tang]

On 11/21/05, "Arun Sharma (अरुण)" <address@hidden> wrote:

> Through a quick grep of the sources, I can't locate anything
> problematic. mempool.h suggests that this is a design guarantee.
>
> So I'm assuming that this is a non-problem for the userspace libunwind.
> Please let me know if you think otherwise.

User-space libunwind assumes that mmap() doesn't acquire any locks so
that's what it's using.  Of course, via dynamic linking magic,
somebody could redefine mmap() to something that does acquire locks,
but there isn't much we can do about that (doing a syscall directly
from libunwind might be an option, but it's non-portable and could
potentially cause other problems).

BTW: You mentioned sigprocmask() showing up high in the profile.  With
caching, that should pretty much disappear (assuming you have
libatomic_ops installed at configure time).

As for the caching in DWARF2: IIRC, the structure you want to cache is
dwarf_cie_t.

  --david
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