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f1de2439ec
iocost has various safety nets to combat inuse adjustment calculation inaccuracies. With Andy's method implemented in transfer_surpluses(), inuse adjustment calculations are now accurate and we can make donation amount determinations accurate too. * Stop keeping track of past usage history and using the maximum. Act on the immediate usage information. * Remove donation constraints defined by SURPLUS_* constants. Donate whatever isn't used. * Determine the donation amount so that the iocg will end up with MARGIN_TARGET_PCT budget at the end of the coming period assuming the same usage as the previous period. TARGET is set at 50% of period, which is the previous maximum. This provides smooth convergence for most repetitive IO patterns. * Apply donation logic early at 20% budget. There's no risk in doing so as the calculation is based on the delta between the current budget and the target budget at the end of the coming period. * Remove preemptive iocg activation for zero cost IOs. As donation can reach near zero now, the mere activation doesn't provide any protection anymore. In the unlikely case that this becomes a problem, the right solution is assigning appropriate costs for such IOs. This significantly improves the donation determination logic while also simplifying it. Now all donations are immediate, exact and smooth. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andy Newell <newella@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
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| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| 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.