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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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67bbd7a8d6
High latencies can be observed caused by a daemon periodically reading CPUID on all cpus. On KASAN enabled kernels ~10ms latencies can be observed. Even without KASAN, sending an IPI to a CPU, which is in a deep sleep state or in a long hard IRQ disabled section, waiting for the answer can consume hundreds of microseconds. cpuid_read() is invoked in preemptible context, so it can be converted to sleep instead of busy wait. Switching to smp_call_function_single_async() and a completion allows to reschedule and reduces CPU usage and latencies. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Eric Dumazet <eric.dumazet@gmail.com> Link: https://lkml.kernel.org/r/20180323215818.127774-2-edumazet@google.com |
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| boot | ||
| configs | ||
| crypto | ||
| entry | ||
| events | ||
| hyperv | ||
| ia32 | ||
| include | ||
| kernel | ||
| kvm | ||
| lib | ||
| math-emu | ||
| mm | ||
| net | ||
| oprofile | ||
| pci | ||
| platform | ||
| power | ||
| purgatory | ||
| ras | ||
| realmode | ||
| tools | ||
| um | ||
| video | ||
| xen | ||
| .gitignore | ||
| Kbuild | ||
| Kconfig | ||
| Kconfig.cpu | ||
| Kconfig.debug | ||
| Makefile | ||
| Makefile_32.cpu | ||
| Makefile.um | ||