c06aed0e31
The jiffies_till_sched_qs value used to determine how old a grace period must be before RCU enlists the help of the scheduler to force a quiescent state on the holdout CPU. Currently, this defaults to HZ/10 regardless of system size and may be set only at boot time. This can be a problem for very large systems, because if the values of the jiffies_till_first_fqs and jiffies_till_next_fqs kernel parameters are left at their defaults, they are calculated to increase as the number of CPUs actually configured on the system increases. Thus, on a sufficiently large system, RCU would enlist the help of the scheduler before the grace-period kthread had a chance to scan for idle CPUs, which wastes CPU time. This commit therefore allows jiffies_till_sched_qs to be set, if desired, but if left as default, computes is as jiffies_till_first_fqs plus twice jiffies_till_next_fqs, thus allowing three force-quiescent-state scans for idle CPUs. This scales with the number of CPUs, providing sensible default values. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> |
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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 | ||
| Kconfig | ||
| 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.