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cabe945876
It has been found that performing a first pass consisting in copying
all messages, and a second one to notify about releases is more efficient
on AMD than updating all of them on the fly using a CAS, despite making
writers wait longer to be released.
Maybe it's related to the ability for the CPU to prefetch the contents
during a simple load while it wouldn't do it for an XCHG, it's unsure
at this point. This will also mater permit to use relaxed stores to
release threads.
On ARM the performance increased to 7.0M/s. If this patch is applied
before the dropping of the intermediary step, instead it drops to
3.9M/s. This shows the dependency between such changes that strive to
limit the number of writes on the fast path.
On x86_64, the EPYC at 3C6T saw a small drop from 4.57M to 4.45M, but
the 24C48T setup saw a nice 33% boost from 3.33M to 4.44M, i.e. we
get stable perf at 3 and 24 cores, despite having 8 CCX involved and
fighting with each other.
Other possibilities are:
- use of HA_ATOMIC_XCHG() instead of FETCH_OR()
=> slightly faster (4.62/7.37 vs 4.58/7.34). Pb: requires to
modify the readers to wait much longer since the tail value
won't be valid in this case during updates, and it will have
to wait by looping over it.
- use other conditions to release a cell
=> to be tested
The HAProxy documentation has been split into a number of different files for ease of use. 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)