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- liburing
- --------
- This is the io_uring library, liburing. liburing provides helpers to setup and
- teardown io_uring instances, and also a simplified interface for
- applications that don't need (or want) to deal with the full kernel
- side implementation.
- For more info on io_uring, please see:
- https://kernel.dk/io_uring.pdf
- Subscribe to io-uring@vger.kernel.org for io_uring related discussions
- and development for both kernel and userspace. The list is archived here:
- https://lore.kernel.org/io-uring/
- kernel version dependency
- --------------------------
- liburing itself is not tied to any specific kernel release, and hence it's
- possible to use the newest liburing release even on older kernels (and vice
- versa). Newer features may only be available on more recent kernels,
- obviously.
- ulimit settings
- ---------------
- io_uring accounts memory it needs under the rlimit memlocked option, which
- can be quite low on some setups (64K). The default is usually enough for
- most use cases, but bigger rings or things like registered buffers deplete
- it quickly. root isn't under this restriction, but regular users are. Going
- into detail on how to bump the limit on various systems is beyond the scope
- of this little blurb, but check /etc/security/limits.conf for user specific
- settings, or /etc/systemd/user.conf and /etc/systemd/system.conf for systemd
- setups. This affects 5.11 and earlier, new kernels are less dependent
- on RLIMIT_MEMLOCK as it is only used for registering buffers.
- Regressions tests
- -----------------
- The bulk of liburing is actually regression/unit tests for both liburing and
- the kernel io_uring support. Please note that this suite isn't expected to
- pass on older kernels, and may even crash or hang older kernels!
- Building liburing
- -----------------
- #
- # Prepare build config (optional).
- #
- # --cc specifies the C compiler.
- # --cxx speficies the C++ compiler.
- #
- ./configure --cc=gcc --cxx=g++;
- #
- # Build liburing.
- #
- make -j$(nproc);
- #
- # Install liburing (headers, shared/static libs, and manpage).
- #
- sudo make install;
- See './configure --help' for more information about build config options.
- FFI support
- -----------
- By default, the build results in 4 lib files:
- 2 shared libs:
- liburing.so
- liburing-ffi.so
- 2 static libs:
- liburing.a
- liburing-ffi.a
- Languages and applications that can't use 'static inline' functions in
- liburing.h should use the FFI variants.
- liburing's main public interface lives in liburing.h as 'static inline'
- functions. Users wishing to consume liburing purely as a binary dependency
- should link against liburing-ffi. It contains definitions for every 'static
- inline' function.
- License
- -------
- All software contained within this repo is dual licensed LGPL and MIT, see
- COPYING and LICENSE, except for a header coming from the kernel which is
- dual licensed GPL with a Linux-syscall-note exception and MIT, see
- COPYING.GPL and <https://spdx.org/licenses/Linux-syscall-note.html>.
- Jens Axboe 2022-05-19
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