f6c3ca0e58
BFQ can deem a bfq_queue as soft real-time only if the queue - periodically becomes completely idle, i.e., empty and with no still-outstanding I/O request; - after becoming idle, gets new I/O only after a special reference time soft_rt_next_start. In this respect, after commit "block, bfq: consider also past I/O in soft real-time detection", the value of soft_rt_next_start can never decrease. This causes a problem with the following special updating case for soft_rt_next_start: to prevent queues that are not completely idle to be wrongly detected as soft real-time (when they become non-empty again), soft_rt_next_start is temporarily set to infinity for empty queues with still outstanding I/O requests. But, if such an update is actually performed, then, because of the above commit, soft_rt_next_start will be stuck at infinity forever, and the queue will have no more chance to be considered soft real-time. On slow systems, this problem does cause actual soft real-time applications to be occasionally not detected as such. This commit addresses this issue by eliminating the pushing of soft_rt_next_start to infinity, and by changing the way non-empty queues are prevented from being wrongly detected as soft real-time. Simply, a queue that becomes non-empty again can now be detected as soft real-time only if it has no outstanding I/O request. Signed-off-by: Davide Sapienza <sapienza.dav@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| firmware | ||
| 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 | ||
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| 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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.