x86: switch config to a tickless kernel

This commit fixes and closes #16313.

Switch the x86 kernel's timer to tickless operation which is
more power efficient since it is not woken up by periodic timer
interrupts when idle.  Also add several other options for CPU
idle governors particularly the upstream default for tickless
kernels, CONFIG_CPU_IDLE_GOV_MENU. Without this commit, my AMD
Ryzen 7 5800U can only achieve a minimum core frequency of 1,384
MHz which is over 3x higher than the processor's minimum
frequency of 400 MHz which is accessible with this modification.
In addition to the lower clock rate, I have seen a concomitant
reduction in both idle temps and at-the-wall power consumption.

Summary:
* Idle CPU freqs dropped from 1,384 MHz to 400 Mhz.
* Idle power consumption dropped from 7 W avg to 5 W.
* Idle temps have dropped from 50C on avg to 43C.

There are other well known reasons to switch to a tickless
timer including: reduced interrupt overhead, better use of CPU
resources, and reduced latency to name a few.

Build system: x86/64
Build-tested: x86/64/AMD Cezanne
Run-tested: x86/64/AMD Cezanne

Signed-off-by: John Audia <therealgraysky@proton.me>
Link: https://github.com/openwrt/openwrt/pull/16317
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

diff --git a/target/linux/x86/config-6.6 b/target/linux/x86/config-6.6
index b8d38e60fa372c25c6f29b19413204a28ce33ad9..3d1c00513852d4691e3738e5c59a64cf792284a2 100644 (file)
--- a/target/linux/x86/config-6.6
+++ b/target/linux/x86/config-6.6
@@ -48,6 +48,7 @@ CONFIG_COMPAT_32=y
 CONFIG_COMPAT_32BIT_TIME=y
 # CONFIG_COMPAT_VDSO is not set
 CONFIG_CONSOLE_TRANSLATIONS=y
+CONFIG_CONTEXT_TRACKING_USER_FORCE=y
 # CONFIG_CPU5_WDT is not set
 CONFIG_CPU_FREQ=y
 CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y
@@ -61,7 +62,10 @@ CONFIG_CPU_FREQ_GOV_PERFORMANCE=y
 # CONFIG_CPU_FREQ_GOV_USERSPACE is not set
 CONFIG_CPU_FREQ_STAT=y
 CONFIG_CPU_IDLE=y
+CONFIG_CPU_IDLE_GOV_HALTPOLL=y
 CONFIG_CPU_IDLE_GOV_LADDER=y
+CONFIG_CPU_IDLE_GOV_MENU=y
+CONFIG_CPU_IDLE_GOV_TEO=y
 CONFIG_CPU_MITIGATIONS=y
 CONFIG_CPU_SUP_AMD=y
 CONFIG_CPU_SUP_CENTAUR=y
@@ -180,7 +184,6 @@ CONFIG_HW_RANDOM=y
 CONFIG_HW_RANDOM_GEODE=y
 CONFIG_HW_RANDOM_VIA=y
 # CONFIG_HYPERVISOR_GUEST is not set
-CONFIG_HZ_PERIODIC=y
 CONFIG_I8253_LOCK=y
 CONFIG_IA32_FEAT_CTL=y
 # CONFIG_IB700_WDT is not set
@@ -275,6 +278,9 @@ CONFIG_NET_XGRESS=y
 CONFIG_NLS=y
 # CONFIG_NMI_CHECK_CPU is not set
 # CONFIG_NOHIGHMEM is not set
+CONFIG_NO_HZ=y
+CONFIG_NO_HZ_COMMON=y
+CONFIG_NO_HZ_FULL=y
 CONFIG_NR_CPUS=1
 CONFIG_NR_CPUS_DEFAULT=1
 CONFIG_NR_CPUS_RANGE_BEGIN=1
@@ -330,6 +336,8 @@ CONFIG_PTP_1588_CLOCK_OPTIONAL=y
 # CONFIG_PUNIT_ATOM_DEBUG is not set
 CONFIG_RANDSTRUCT_NONE=y
 CONFIG_RATIONAL=y
+CONFIG_RCU_LAZY=y
+CONFIG_RCU_NOCB_CPU_DEFAULT_ALL=y
 CONFIG_RD_BZIP2=y
 CONFIG_RD_GZIP=y
 CONFIG_RETHUNK=y