forked from luck/tmp_suning_uos_patched
7cd806a9a9
Some IOs may span multiple periods. As latencies are collected on completion, the inbetween periods won't register them and may incorrectly decide to increase vrate. nr_lagging tracks these IOs to avoid those situations. Currently, whenever there are IOs which are spanning from the previous period, busy_level is reset to 0 if negative thus suppressing vrate increase. This has the following two problems. * When latency target percentiles aren't set, vrate adjustment should only be governed by queue depth depletion; however, the current code keeps nr_lagging active which pulls in latency results and can keep down vrate unexpectedly. * When lagging condition is detected, it resets the entire negative busy_level. This turned out to be way too aggressive on some devices which sometimes experience extended latencies on a small subset of commands. In addition, a lagging IO will be accounted as latency target miss on completion anyway and resetting busy_level amplifies its impact unnecessarily. This patch fixes the above two problems by disabling nr_lagging counting when latency target percentiles aren't set and blocking vrate increases when there are lagging IOs while leaving busy_level as-is. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| 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 | ||
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.