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5b06d1679f
KVM supports msgsndp in guests by trapping and emulating the instruction, so it was decided to always use XIVE for IPIs if it is available. However on PowerVM systems, msgsndp can be used and gives better performance. On large systems, high XIVE interrupt rates can have sub-linear scaling, and using msgsndp can reduce the load on the interrupt controller. So switch to using core local doorbells even if XIVE is available. This reduces performance for KVM guests with an SMT topology by about 50% for ping-pong context switching between SMT vCPUs. An option vector (or dt-cpu-ftrs) could be defined to disable msgsndp to get KVM performance back. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Tested-by: Cédric Le Goater <clg@kaod.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200726035155.1424103-3-npiggin@gmail.com |
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| 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.