20e60a3832
As submission references are gone, there is only one initial reference left. Instead of actually doing atomic refcounting, add a flag indicating whether we're going to take more refs or doing any other sync magic. The flag should be set before the request may get used in parallel. Together with the previous patch it saves 2 refcount atomics per request for IOPOLL and IRQ completions, and 1 atomic per req for inline completions, with some exceptions. In particular, currently, there are three cases, when the refcounting have to be enabled: - Polling, including apoll. Because double poll entries takes a ref. Might get relaxed in the near future. - Link timeouts, enabled for both, the timeout and the request it's bound to, because they work in-parallel and we need to synchronise to cancel one of them on completion. - When a request gets in io-wq, because it doesn't hold uring_lock and we need guarantees of submission references. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/8b204b6c5f6643062270a1913d6d3a7f8f795fd9.1628705069.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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.