8f09bdce10
The buffer ring is problematic in multiple aspects, one of which being that it is only usable by one entity. With multiplexed protocols, we need to have shared buffers used by many entities (streams and connection), and the only way to use the buffer ring model in this case is to have each entity store its own array, and keep a shared counter on allocated entries. But even with the default 32 buf and 100 streams per HTTP/2 connection, we're speaking about 32*101*32 bytes = 103424 bytes per H2 connection, just to store up to 32 shared buffers, spread randomly in these tables. Some users might want to achieve much higher than default rates over high speed links (e.g. 30-50 MB/s at 100ms), which is 3 to 5 MB storage per connection, hence 180 to 300 buffers. There it starts to cost a lot, up to 1 MB per connection, just to store buffer indexes. Instead this patch introduces a variant which we call a buffer list. That's basically just a free list encoded in an array. Each cell contains a buffer structure, a next index, and a few flags. The index could be reduced to 16 bits if needed, in order to make room for a new struct member. The design permits initializing a whole freelist at once using memset(0). The list pointer is stored at a single location (e.g. the connection) and all users (the streams) will just have indexes referencing their first and last assigned entries (head and tail). This means that with a single table we can now have all our buffers shared between multiple streams, irrelevant to the number of potential streams which would want to use them. Now the 180 to 300 entries array only costs 7.2 to 12 kB, or 80 times less. Two large functions (bl_deinit() & bl_get()) were implemented in buf.c. A basic doc was added to explain how it works. |
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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.