For debugging/comparison purposes there is also support for the "idle=nomwait" kernel option if wanting to avoid using MWAIT and return to the old halt instruction use.Īlso notable on the AMD Linux side this Monday morning is the x86/misc pull. With the vendor checks dropped, AMD CPUs will now happily use MWAIT over HLT in the generic x86 CPU idle code path. More good news for AMD HPC customers with Linux 6.0. This change for Linux 6.0 can mean ~21% lower exit latency on Zen 3 from idle though primarily benefits AMD HPC customers who disable global C-states from the BIOS. However, with newer AMD Zen processors, using MWAIT over HALT is preferred within the C1 power management code for the Linux kernel as using MWAIT over C1 has lower exit latency / more efficient.
This vendor checking was just for Intel CPUs to use MWAIT over HALT due to issues with older AMD processors. Among the early pull requests for the now-open Linux 6.0 merge window ( nee Linux 5.20) are a few AMD additions worth mentioning.įirst up is the x86/cpu pull that now drops the vendor checks from the "prefer_mwait_c1_over_halt" function.
0 kommentar(er)
