Improve default '-smp' value #57
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nathanchance
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msfjarvis,
nickdesaulniers and
tpimh
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msfjarvis
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Mar 12, 2022
As noted on the review for ClangBuiltLinux#17, when booting an i386_defconfig kernel, there is a lot of spam in the boot logs because CONFIG_NR_CPUS is set to 8: [ 0.020644] APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 8/0x8 ignored. [ 0.021302] APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 9/0x9 ignored. [ 0.021964] APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 10/0xa ignored. [ 0.022642] APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 11/0xb ignored. With large machines, this can be quite noisy, as there is one print out for every CPU above 8. Refactor the logic for finding a sensible value based on CONFIG_NR_CPUS if a config can be found. If no config is available, default to 8, which is the default value for i386_defconfig. Signed-off-by: Nathan Chancellor <nathan@kernel.org>
For both ARCH=arm and ARCH=arm64 defconfig, the default of get_default_smp_value when there is no configuration available will work. Signed-off-by: Nathan Chancellor <nathan@kernel.org>
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Signed-off-by: Nathan Chancellor <nathan@kernel.org>
nickdesaulniers
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Mar 17, 2022
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This series implements a heuristic for the default '-smp' value when KVM is used and uses '-smp' for arm and arm64 KVM for better performance.