aio: Squash aio_nowait_supported into fs_info::nowait_works #2893
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When setting up aiocb, the set_nowait() helper checks two bits: - global aio_nowait_supported, which comes from CLI option whose default value depends on the kernel uname - per-request nowait_works, which is inherited from file that gets it from fs_info object filled based on filesystem type and, again, kernel uname value This patch removes the global bit, keeps the respective CLI option on reactor config and then updates the per-filesystem fs_info nowait_works with it. "While at it" drop few unneeded forward declaration. Signed-off-by: Pavel Emelyanov <[email protected]>
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Pull Request Overview
This PR refactors AIO nowait support by consolidating the global aio_nowait_supported variable into the per-filesystem fs_info::nowait_works field. Instead of checking both a global flag and per-filesystem setting, the code now uses only the per-filesystem setting which is updated with the reactor configuration value.
Key changes:
- Removes the global
aio_nowait_supportedvariable and related forward declarations - Adds
aio_nowait_worksfield toreactor_configstructure - Updates filesystem-specific nowait detection to combine with reactor configuration
- Simplifies the
set_nowait()function to remove the global check
Reviewed Changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| tests/unit/file_io_test.cc | Updates test to use new reactor test API instead of global variable |
| src/core/reactor_backend.cc | Removes unused forward declaration of global variable |
| src/core/reactor.cc | Removes global variable, adds reactor config field and test API |
| src/core/file.cc | Updates filesystem info to combine with reactor configuration |
| include/seastar/core/reactor_config.hh | Adds aio_nowait_works field to reactor configuration |
| include/seastar/core/reactor.hh | Adds test API for accessing nowait configuration |
| include/seastar/core/linux-aio.hh | Simplifies set_nowait function and removes global variable declaration |
| @@ -3869,7 +3869,7 @@ reactor_options::reactor_options(program_options::option_group* parent_group) | |||
| , blocked_reactor_reports_per_minute(*this, "blocked-reactor-reports-per-minute", 5, "Maximum number of backtraces reported by stall detector per minute") | |||
| , blocked_reactor_report_format_oneline(*this, "blocked-reactor-report-format-oneline", true, "Print a simplified backtrace on a single line") | |||
| , relaxed_dma(*this, "relaxed-dma", "allow using buffered I/O if DMA is not available (reduces performance)") | |||
| , linux_aio_nowait(*this, "linux-aio-nowait", aio_nowait_supported, | |||
| , linux_aio_nowait(*this, "linux-aio-nowait", internal::kernel_uname().whitelisted({"4.13"}), // base version where this works | |||
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[nitpick] The inline comment should be moved to a separate line or expanded to better explain the significance of kernel version 4.13 for AIO nowait support.
Suggested change
| , linux_aio_nowait(*this, "linux-aio-nowait", internal::kernel_uname().whitelisted({"4.13"}), // base version where this works | |
| // The Linux AIO NOWAIT feature, which allows asynchronous I/O operations to return immediately if they would block, | |
| // was introduced in Linux kernel version 4.13. This option is only enabled on kernels 4.13 and newer. | |
| , linux_aio_nowait(*this, "linux-aio-nowait", internal::kernel_uname().whitelisted({"4.13"}), |
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When setting up aiocb, the set_nowait() helper checks two bits:
This patch removes the global bit, keeps the respective CLI option on reactor config and then updates the per-filesystem fs_info nowait_works with it.
"While at it" drop few unneeded forward declaration.