Linux mainline fork with MSM8998 patches | https://mainline.space | Currently supported devices:
OnePlus 5/5T, Xiaomi Mi 6, F(x)tec Pro¹ (2019 QX1000 model) & Sony Xperia XZ Premium (UNTESTED!)
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Consider a sync bfq_queue Q that remains empty while in service, and suppose that, when this happens, there is a fair amount of already in-flight I/O not belonging to Q. In such a situation, I/O dispatching may need to be plugged (until new I/O arrives for Q), for the following reason. The drive may decide to serve in-flight non-Q's I/O requests before Q's ones, thereby delaying the arrival of new I/O requests for Q (recall that Q is sync). If I/O-dispatching is not plugged, then, while Q remains empty, a basically uncontrolled amount of I/O from other queues may be dispatched too, possibly causing the service of Q's I/O to be delayed even longer in the drive. This problem gets more and more serious as the speed and the queue depth of the drive grow, because, as these two quantities grow, the probability to find no queue busy but many requests in flight grows too. If Q has the same weight and priority as the other queues, then the above delay is unlikely to cause any issue, because all queues tend to undergo the same treatment. So, since not plugging I/O dispatching is convenient for throughput, it is better not to plug. Things change in case Q has a higher weight or priority than some other queue, because Q's service guarantees may simply be violated. For this reason, commit |
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| 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.