23fe1a52dc
Currently, we use `pipe` for `wakeup_create`, which requires ***two***
file descriptors. Furthermore, given its complexity inside, `pipe` is a
bit heavyweight for just a simple event wait/notify mechanism.
`eventfd` would be a more suitable solution for this kind of scenario,
kernel also advocates for developers to use `eventfd` instead of `pipe`
in some simple use cases:
Applications can use an eventfd file descriptor instead of a pipe
(see pipe(2) in all cases where a pipe is used simply to signal
events. The kernel overhead of an eventfd file descriptor is much
lower than that of a pipe, and only one file descriptor is required
(versus the two required for a pipe).
This change adds the new backend of `eventfd` for `wakeup_create` and
uses it where available, eliminating the overhead of `pipe`. Also, it
optimizes the `wakeup_create` to eliminate the system calls that make
file descriptors non-blocking by moving the logic of setting
non-blocking flags on file descriptors to `socketpair.c` and using
`SOCK_NONBLOCK` for `socketpair(2)`, `EFD_NONBLOCK` for `eventfd(2)`.
Ref:
https://man7.org/linux/man-pages/man7/pipe.7.html
https://man7.org/linux/man-pages/man2/eventfd.2.html
https://man7.org/linux/man-pages/man2/socketpair.2.html
https://www.gnu.org/software/gnulib/manual/html_node/eventfd.html
Closes #13874
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| .circleci | ||
| .github | ||
| .reuse | ||
| CMake | ||
| docs | ||
| include | ||
| lib | ||
| LICENSES | ||
| m4 | ||
| packages | ||
| plan9 | ||
| projects | ||
| scripts | ||
| src | ||
| tests | ||
| winbuild | ||
| .azure-pipelines.yml | ||
| .cirrus.yml | ||
| .dcignore | ||
| .dir-locals.el | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| acinclude.m4 | ||
| appveyor.sh | ||
| appveyor.yml | ||
| buildconf | ||
| buildconf.bat | ||
| CHANGES | ||
| CMakeLists.txt | ||
| configure.ac | ||
| COPYING | ||
| curl-config.in | ||
| Dockerfile | ||
| GIT-INFO.md | ||
| libcurl.def | ||
| libcurl.pc.in | ||
| Makefile.am | ||
| Makefile.dist | ||
| maketgz | ||
| README | ||
| README.md | ||
| RELEASE-NOTES | ||
| renovate.json | ||
| SECURITY.md | ||
Curl is a command-line tool for transferring data specified with URL syntax. Find out how to use curl by reading the curl.1 man page or the MANUAL document. Find out how to install Curl by reading the INSTALL document.
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