a79a67b52f
The code in srv_add_to_idle_list() has its roots in 2.0 with commit
9ea5d361ae ("MEDIUM: servers: Reorganize the way idle connections are
cleaned."). At this era we didn't yet have the current set of atomic
load/store operations and we used to perform loads using volatile casts
after a barrier. It turns out that this function has kept this schema
over the years, resulting in a big mfence stalling all the pipeline
in the function:
| static __inline void
| __ha_barrier_full(void)
| {
| __asm __volatile("mfence" ::: "memory");
27.08 | mfence
| if ((volatile void *)srv->idle_node.node.leaf_p == NULL) {
0.84 | cmpq $0x0,0x158(%r15)
0.74 | je 35f
| return 1;
Switching these for a pair of atomic loads got rid of this and brought
0.5 to 3% extra performance depending on the tests due to variations
elsewhere, but it has never been below 0.5%. Note that the second load
doesn't need to be atomic since it's protected by the lock, but it's
cleaner from an API and code review perspective. That's also why it's
relaxed.
This was the last user of _ha_barrier_full(), let's try not to
reintroduce it now!
HAProxy
HAProxy is a free, very fast and reliable reverse-proxy offering high availability, load balancing, and proxying for TCP and HTTP-based applications.
Installation
The INSTALL file describes how to build HAProxy. A list of packages is also available on the wiki.
Getting help
The discourse and the mailing-list are available for questions or configuration assistance. You can also use the slack or IRC channel. Please don't use the issue tracker for these.
The issue tracker is only for bug reports or feature requests.
Documentation
The HAProxy documentation has been split into a number of different files for ease of use. It is available in text format as well as HTML. The wiki is also meant to replace the old architecture guide.
Please refer to the following files depending on what you're looking for:
- INSTALL for instructions on how to build and install HAProxy
- BRANCHES to understand the project's life cycle and what version to use
- LICENSE for the project's license
- CONTRIBUTING for the process to follow to submit contributions
The more detailed documentation is located into the doc/ directory:
- doc/intro.txt for a quick introduction on HAProxy
- doc/configuration.txt for the configuration's reference manual
- doc/lua.txt for the Lua's reference manual
- doc/SPOE.txt for how to use the SPOE engine
- doc/network-namespaces.txt for how to use network namespaces under Linux
- doc/management.txt for the management guide
- doc/regression-testing.txt for how to use the regression testing suite
- doc/peers.txt for the peers protocol reference
- doc/coding-style.txt for how to adopt HAProxy's coding style
- doc/internals for developer-specific documentation (not all up to date)
License
HAProxy is licensed under GPL 2 or any later version, the headers under LGPL 2.1. See the LICENSE file for a more detailed explanation.