b41e98524e
For poll requests, it's not uncommon to link a read (or write) after the poll to execute immediately after the file is marked as ready. Since the poll completion is called inside the waitqueue wake up handler, we have to punt that linked request to async context. This slows down the processing, and actually means it's faster to not use a link for this use case. We also run into problems if the completion_lock is contended, as we're doing a different lock ordering than the issue side is. Hence we have to do trylock for completion, and if that fails, go async. Poll removal needs to go async as well, for the same reason. eventfd notification needs special case as well, to avoid stack blowing recursion or deadlocks. These are all deficiencies that were inherited from the aio poll implementation, but I think we can do better. When a poll completes, simply queue it up in the task poll list. When the task completes the list, we can run dependent links inline as well. This means we never have to go async, and we can remove a bunch of code associated with that, and optimizations to try and make that run faster. The diffstat speaks for itself. Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.