So far we relied on getting EINVAL in CQE for operations that kernel don't
support. The problem with that approach is that there are many other reasons
(like wrong params) to get EINVAL. The other problem is when we have an
operation that existed before and gets new behavior via different attributes,
like accept and accept_direct. Older kernels can fall back to non direct
operation although we set attributes for direct operation. Operation completes
successfully in both cases but with different results.
This commit introduces kernel version check at the start of the test. Making
body of the test free of checking for various kernel version differences.
Feature availability references:
* https://manpages.debian.org/unstable/liburing-dev/io_uring_enter.2.en.html
* https://kernel.dk/axboe-kr2022.pdf
* 5acf7969bc/lib/std/os/linux.zig (L3727)
* 5acf7969bc/lib/std/os/linux.zig (L3993)
`send_zc` tries to avoid making intermediate copies of data. Zerocopy execution
is not guaranteed and may fall back to copying.
The flags field of the first struct io_uring_cqe may likely contain
IORING_CQE_F_MORE , which means that there will be a second completion event /
notification for the request, with the user_data field set to the same value.
The user must not modify the data buffer until the notification is posted. The
first cqe follows the usual rules and so its res field will contain the number
of bytes sent or a negative error code. The notification's res field will be set
to zero and the flags field will contain IORING_CQE_F_NOTIF. The two step model
is needed because the kernel may hold on to buffers for a long time, e.g.
waiting for a TCP ACK, and having a separate cqe for request completions allows
userspace to push more data without extra delays. Note, notifications are only
responsible for controlling the lifetime of the buffers, and as such don't mean
anything about whether the data has atually been sent out or received by the
other end. Even errored requests may generate a notification, and the user must
check for IORING_CQE_F_MORE rather than relying on the result.
Available since kernel 6.0.
References:
https://man7.org/linux/man-pages/man3/io_uring_prep_send_zc.3.htmlhttps://man7.org/linux/man-pages/man2/io_uring_enter.2.html
There is no grantee that `copy_cqes` will return exactly wait_nr number of cqes.
If there are ready cqes it can return > 0 but < wait_nr number of cqes.
Server networking application typically accept multiple connections. Multishot
accept simplifies handling these situations. Applications submits once and
receives CQE whenever a new connection request comes in.
Multishot is active until it is canceled or experience error. While active, and
further notification are expected CQE completion will have IORING_CQE_F_MORE set
in the flags. If this flag isn't set, the application must re-arm this request
by submitting a new one.
Reference: [io_uring and networking in 2023](https://github.com/axboe/liburing/wiki/io_uring-and-networking-in-2023#multi-shot)
* 128-bit integer multiplication with overflow
* more instruction encodings used by std inline asm
* implement the `try_ptr` air instruction
* follow correct stack frame abi
* enable full panic handler
* enable stack traces
This reverts commit 0c99ba1eab, reversing
changes made to 5f92b070bf.
This caused a CI failure when it landed in master branch due to a
128-bit `@byteSwap` in std.mem.
Insn.st() can be used with dynamic size just like Insn.stx(), which is
relevant in a code generation context.
using ImmOrReg caused an error as its fields were ordered differently than
Source.
After fixing some issues with inline assembly in the C backend, the std
cleanups have the side effect of making these functions compatible with
the backend, allowing it to be used on linux without linking libc.
- Fix unwindFrame using the previous FDE row instead of the current one
- Handle unwinding through noreturn functions
- Add x86-linux getcontext
- Fixup x86_64-linux getcontext not restoring the fp env
- Fix start_addr filtering on x86-windows
* `CMakeLists.txt`: support the weird `uname -m` output.
* `CMakeLists.txt`: detect and use the C compiler's default arm mode.
* cbe: support gcc with both `f128` and `u128` emulated.
* std.os.linux.thumb: fix incorrectly passed asm inputs.
Most of this migration was performed automatically with `zig fmt`. There
were a few exceptions which I had to manually fix:
* `@alignCast` and `@addrSpaceCast` cannot be automatically rewritten
* `@truncate`'s fixup is incorrect for vectors
* Test cases are not formatted, and their error locations change
Anecdote 1: The generic version is way more popular than the non-generic
one in Zig codebase:
git grep -w alignForward | wc -l
56
git grep -w alignForwardGeneric | wc -l
149
git grep -w alignBackward | wc -l
6
git grep -w alignBackwardGeneric | wc -l
15
Anecdote 2: In my project (turbonss) that does much arithmetic and
alignment I exclusively use the Generic functions.
Anecdote 3: we used only the Generic versions in the Macho Man's linker
workshop.
The majority of these are in comments, some in doc comments which might
affect the generated documentation, and a few in parameter names -
nothing that should be breaking, however.
* docs(std.math): elaborate on difference between absCast and absInt
* docs(std.rand.Random.weightedIndex): elaborate on likelihood
I think this makes it easier to understand.
* langref: add small reminder
* docs(std.fs.path.extension): brevity
* docs(std.bit_set.StaticBitSet): mention the specific types
* std.debug.TTY: explain what purpose this struct serves
This should also make it clearer that this struct is not supposed to provide unrelated terminal manipulation functionality such as setting the cursor position or something because terminals are complicated and we should keep this struct simple and focused on debugging.
* langref(package listing): brevity
* langref: explain what exactly `threadlocal` causes to happen
* std.array_list: link between swapRemove and orderedRemove
Maybe this can serve as a TLDR and make it easier to decide.
* PrefetchOptions.locality: clarify docs that this is a range
This confused me previously and I thought I can only use either 0 or 3.
* fix typos and more
* std.builtin.CallingConvention: document some CCs
* langref: explain possibly cryptic names
I think it helps knowing what exactly these acronyms (@clz and @ctz) and
abbreviations (@popCount) mean.
* variadic function error: add missing preposition
* std.fmt.format docs: nicely hyphenate
* help menu: say what to optimize for
I think this is slightly more specific than just calling it
"optimizations". These are speed optimizations. I used the word
"performance" here.
