OVS is slow when compiled with pthreads atomics. Add a generic note
in INSTALL, with a reference to lib/ovs-atomic.h, where a new comment
provides additional detail.
Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com>
---
INSTALL | 4 ++++
lib/ovs-atomic.h | 3 +++
2 files changed, 7 insertions(+)
diff --git a/INSTALL b/INSTALL
index 5c869b2..7b08172 100644
--- a/INSTALL
+++ b/INSTALL
@@ -28,6 +28,10 @@ you will need the following software:
analysis and thread-safety checks. For Ubuntu, there are
nightly built packages available on clang's website.
+ * While OVS may be compatible with other compilers, optimal
+ support for atomic operations may be missing, making OVS
+ very slow (see lib/ovs-atomic.h).
+
- libssl, from OpenSSL, is optional but recommended if you plan to
connect the Open vSwitch to an OpenFlow controller. libssl is
required to establish confidentiality and authenticity in the
diff --git a/lib/ovs-atomic.h b/lib/ovs-atomic.h
index c21b7ee..2452846 100644
--- a/lib/ovs-atomic.h
+++ b/lib/ovs-atomic.h
@@ -257,6 +257,9 @@
#elif HAVE_GCC4_ATOMICS
#include "ovs-atomic-gcc4+.h"
#else
+ /* ovs-atomic-pthreads implementation is provided for portability.
+ * It might be too slow for real use because Open vSwitch is
+ * optimized for platforms where real atomic ops are available. */
#include "ovs-atomic-pthreads.h"
#endif
#undef IN_OVS_ATOMIC_H
--
1.7.10.4
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