a240c4aa5d
If the current P-state selection algorithm is set to "performance" in intel_pstate_set_policy(), the limits may be initialized from scratch, but only if no_turbo is not set and the maximum frequency allowed for the given CPU (i.e. the policy object representing it) is at least equal to the max frequency supported by the CPU. In all of the other cases, the limits will not be updated. For example, the following can happen: # cat intel_pstate/status active # echo performance > cpufreq/policy0/scaling_governor # cat intel_pstate/min_perf_pct 100 # echo 94 > intel_pstate/min_perf_pct # cat intel_pstate/min_perf_pct 100 # cat cpufreq/policy0/scaling_max_freq 3100000 echo 3000000 > cpufreq/policy0/scaling_max_freq # cat intel_pstate/min_perf_pct 94 # echo 95 > intel_pstate/min_perf_pct # cat intel_pstate/min_perf_pct 95 That is confusing for two reasons. First, the initial attempt to change min_perf_pct to 94 seems to have no effect, even though setting the global limits should always work. Second, after changing scaling_max_freq for policy0 the global min_perf_pct attribute shows 94, even though it should have not been affected by that operation in principle. Moreover, the final attempt to change min_perf_pct to 95 worked as expected, because scaling_max_freq for the only policy with scaling_governor equal to "performance" was different from the maximum at that time. To make all that confusion go away, modify intel_pstate_set_policy() so that it doesn't reinitialize the limits at all. At the same time, change intel_pstate_set_performance_limits() to set min_sysfs_pct to 100 in the "performance" limits set so that switching the P-state selection algorithm to "performance" causes intel_pstate/min_perf_pct in sysfs to go to 100 (or whatever value min_sysfs_pct in the "performance" limits is set to later). That requires per-CPU limits to be initialized explicitly rather than by copying the global limits to avoid setting min_sysfs_pct in the per-CPU limits to 100. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> |
||
|---|---|---|
| Documentation | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.