tree c8411ff290dac6102131bef4c719dfd077381693
parent 158ef8cbb7e0fe8bb430310924b8bebe5f186e6e
author Paolo Bonzini <pbonzini@redhat.com> 1368444587 +0200
committer Paolo Bonzini <pbonzini@redhat.com> 1422892510 +0100

rcu: add rcu library

This includes a (mangled) copy of the liburcu code.  The main changes
are: 1) removing dependencies on many other header files in liburcu; 2)
removing for simplicity the tentative busy waiting in synchronize_rcu,
which has limited performance effects; 3) replacing futexes in
synchronize_rcu with QemuEvents for Win32 portability.  The API is
the same as liburcu, so it should be possible in the future to require
liburcu on POSIX systems for example and use our copy only on Windows.

Among the various versions available I chose urcu-mb, which is the
least invasive implementation even though it does not have the
fastest rcu_read_{lock,unlock} implementation.  The urcu flavor can
be changed later, after benchmarking.

Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>