From bfad634454323ac848fbd54baffcc583710e5ea6 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Jul 19 2022 07:55:18 +0000 Subject: config: Remove acpi_idle and intel_idle command lines options These options were set historically to limits C-states but over time, these have become less useful and potentially hazardous. 1. The C1 state may not exist due to BIOS settings. For example, C1 may not be enabled, but C1E does resulting in excessive polling and a failure to ever idle. 2. There may be no idle driver at all if its disabled in the BIOS 3. The idle driver for the machine could be CPPC-based in which case the option is simply ignored. The decision to limit c-states should be an explicit decision for a deployment and limited either via the command line or more reliably via /dev/cpu_dma_latency. --- diff --git a/config/x86_64/rt b/config/x86_64/rt index 17d1051..3d967ed 100644 --- a/config/x86_64/rt +++ b/config/x86_64/rt @@ -526,7 +526,7 @@ CONFIG_HOTPLUG_CPU=y CONFIG_LEGACY_VSYSCALL_XONLY=y # CONFIG_LEGACY_VSYSCALL_NONE is not set CONFIG_CMDLINE_BOOL=y -CONFIG_CMDLINE="processor.max_cstate=1 intel_idle.max_cstate=1 skew_tick=1" +CONFIG_CMDLINE="skew_tick=1" # CONFIG_CMDLINE_OVERRIDE is not set CONFIG_MODIFY_LDT_SYSCALL=y # CONFIG_STRICT_SIGALTSTACK_SIZE is not set diff --git a/patches.rt/rt-Add-documentation-describing-what-RT-kernel-config-changes-to-default.patch b/patches.rt/rt-Add-documentation-describing-what-RT-kernel-config-changes-to-default.patch index 927ccaf..fdba55e 100644 --- a/patches.rt/rt-Add-documentation-describing-what-RT-kernel-config-changes-to-default.patch +++ b/patches.rt/rt-Add-documentation-describing-what-RT-kernel-config-changes-to-default.patch @@ -11,6 +11,18 @@ The RT configuration is derived from the SLE kernel but over time it can drift. Add a patch describing the config options that change so that it can potentially be auto-generated. +LOCALVERSION: Mandatory for flavour +PREEMPT_DYNAMIC +PREEMPT_RT +PREEMPT_RRCU Mandatory for RT +RCU_BOOST Boost RCU or RT task can starve completion of RCU GP +RCU_BOOST_DELAY Default value +RT_GROUP_SCHED Disabled as it complicates configuration for non-root users +CMDLINE skew_tick moderates jitter on largerr systems +BCACHE Disabled historically for stability reasons +PREEMPT_TRACER Disabled due to overhead, enabled on rt_debug +DEBUG_PREEMPT Disabled due to overhead, enabled on rt_debug + Signed-off-by: Mel Gorman --- @@ -31,7 +43,7 @@ index 000000000000..71aae908c52c +value:CONFIG_RCU_BOOST_DELAY:500 +unset:CONFIG_RT_GROUP_SCHED +set:CONFIG_CMDLINE_BOOL -+value:CONFIG_CMDLINE:"processor.max_cstate=1 intel_idle.max_cstate=1 skew_tick=1" ++value:CONFIG_CMDLINE:"skew_tick=1" +unset:CONFIG_BCACHE +unset:CONFIG_PREEMPT_TRACER +unset:CONFIG_DEBUG_PREEMPT