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* [PATCH AUTOSEL 5.18 01/53] x86: Handle idle=nomwait cmdline properly for x86_idle
@ 2022-08-08  1:32 Sasha Levin
  2022-08-08  1:32 ` [PATCH AUTOSEL 5.18 02/53] arch: make TRACE_IRQFLAGS_NMI_SUPPORT generic Sasha Levin
                   ` (51 more replies)
  0 siblings, 52 replies; 75+ messages in thread
From: Sasha Levin @ 2022-08-08  1:32 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Wyes Karny, Dave Hansen, Zhang Rui, Sasha Levin, rafael,
	daniel.lezcano, corbet, tglx, mingo, bp, x86, peterz,
	chang.seok.bae, ebiederm, zhengqi.arch, linux-pm, linux-doc

From: Wyes Karny <wyes.karny@amd.com>

[ Upstream commit 8bcedb4ce04750e1ccc9a6b6433387f6a9166a56 ]

When kernel is booted with idle=nomwait do not use MWAIT as the
default idle state.

If the user boots the kernel with idle=nomwait, it is a clear
direction to not use mwait as the default idle state.
However, the current code does not take this into consideration
while selecting the default idle state on x86.

Fix it by checking for the idle=nomwait boot option in
prefer_mwait_c1_over_halt().

Also update the documentation around idle=nomwait appropriately.

[ dhansen: tweak commit message ]

Signed-off-by: Wyes Karny <wyes.karny@amd.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lkml.kernel.org/r/fdc2dc2d0a1bc21c2f53d989ea2d2ee3ccbc0dbe.1654538381.git-series.wyes.karny@amd.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 Documentation/admin-guide/pm/cpuidle.rst | 15 +++++++++------
 arch/x86/kernel/process.c                |  9 ++++++---
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/Documentation/admin-guide/pm/cpuidle.rst b/Documentation/admin-guide/pm/cpuidle.rst
index aec2cd2aaea7..19754beb5a4e 100644
--- a/Documentation/admin-guide/pm/cpuidle.rst
+++ b/Documentation/admin-guide/pm/cpuidle.rst
@@ -612,8 +612,8 @@ the ``menu`` governor to be used on the systems that use the ``ladder`` governor
 by default this way, for example.
 
 The other kernel command line parameters controlling CPU idle time management
-described below are only relevant for the *x86* architecture and some of
-them affect Intel processors only.
+described below are only relevant for the *x86* architecture and references
+to ``intel_idle`` affect Intel processors only.
 
 The *x86* architecture support code recognizes three kernel command line
 options related to CPU idle time management: ``idle=poll``, ``idle=halt``,
@@ -635,10 +635,13 @@ idle, so it very well may hurt single-thread computations performance as well as
 energy-efficiency.  Thus using it for performance reasons may not be a good idea
 at all.]
 
-The ``idle=nomwait`` option disables the ``intel_idle`` driver and causes
-``acpi_idle`` to be used (as long as all of the information needed by it is
-there in the system's ACPI tables), but it is not allowed to use the
-``MWAIT`` instruction of the CPUs to ask the hardware to enter idle states.
+The ``idle=nomwait`` option prevents the use of ``MWAIT`` instruction of
+the CPU to enter idle states. When this option is used, the ``acpi_idle``
+driver will use the ``HLT`` instruction instead of ``MWAIT``. On systems
+running Intel processors, this option disables the ``intel_idle`` driver
+and forces the use of the ``acpi_idle`` driver instead. Note that in either
+case, ``acpi_idle`` driver will function only if all the information needed
+by it is in the system's ACPI tables.
 
 In addition to the architecture-level kernel command line options affecting CPU
 idle time management, there are parameters affecting individual ``CPUIdle``
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 622dc3673c37..8011536ba5c4 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -824,6 +824,10 @@ static void amd_e400_idle(void)
  */
 static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
 {
+	/* User has disallowed the use of MWAIT. Fallback to HALT */
+	if (boot_option_idle_override == IDLE_NOMWAIT)
+		return 0;
+
 	if (c->x86_vendor != X86_VENDOR_INTEL)
 		return 0;
 
@@ -932,9 +936,8 @@ static int __init idle_setup(char *str)
 	} else if (!strcmp(str, "nomwait")) {
 		/*
 		 * If the boot option of "idle=nomwait" is added,
-		 * it means that mwait will be disabled for CPU C2/C3
-		 * states. In such case it won't touch the variable
-		 * of boot_option_idle_override.
+		 * it means that mwait will be disabled for CPU C1/C2/C3
+		 * states.
 		 */
 		boot_option_idle_override = IDLE_NOMWAIT;
 	} else
-- 
2.35.1


^ permalink raw reply related	[flat|nested] 75+ messages in thread

end of thread, other threads:[~2022-08-08  2:07 UTC | newest]

Thread overview: 75+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-08-08  1:32 [PATCH AUTOSEL 5.18 01/53] x86: Handle idle=nomwait cmdline properly for x86_idle Sasha Levin
2022-08-08  1:32 ` [PATCH AUTOSEL 5.18 02/53] arch: make TRACE_IRQFLAGS_NMI_SUPPORT generic Sasha Levin
2022-08-08  1:32 ` [PATCH AUTOSEL 5.18 03/53] arm64: kernel: drop unnecessary PoC cache clean+invalidate Sasha Levin
2022-08-08  1:32   ` Sasha Levin
2022-08-08  1:32 ` [PATCH AUTOSEL 5.18 04/53] arm64: mm: provide idmap pointer to cpu_replace_ttbr1() Sasha Levin
2022-08-08  1:32   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 05/53] arm64: kaslr: defer initialization to initcall where permitted Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 06/53] arm64: Do not forget syscall when starting a new thread Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 07/53] arm64: fix oops in concurrently setting insn_emulation sysctls Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 08/53] mm: kasan: Ensure the tags are visible before the tag in page->flags Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 09/53] mm: kasan: Skip unpoisoning of user pages Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 10/53] mm: kasan: Skip page unpoisoning only if __GFP_SKIP_KASAN_UNPOISON Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 11/53] arm64: kasan: Revert "arm64: mte: reset the page tag in page->flags" Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 12/53] arm64: errata: Remove AES hwcap for COMPAT tasks Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 13/53] ext2: Add more validity checks for inode counts Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 14/53] sched/fair: Introduce SIS_UTIL to search idle CPU based on sum of util_avg Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 15/53] genirq: Don't return error on missing optional irq_request_resources() Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 16/53] irqchip/mips-gic: Only register IPI domain when SMP is enabled Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 17/53] genirq: GENERIC_IRQ_IPI depends on SMP Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 18/53] sched/fair: fix case with reduced capacity CPU Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 19/53] sched/core: Always flush pending blk_plug Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 20/53] irqchip/mips-gic: Check the return value of ioremap() in gic_of_init() Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 21/53] wait: Fix __wait_event_hrtimeout for RT/DL tasks Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 22/53] ARM: dts: imx6ul: add missing properties for sram Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 23/53] ARM: dts: imx6ul: change operating-points to uint32-matrix Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 24/53] ARM: dts: imx6ul: fix keypad compatible Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 25/53] ARM: dts: imx6ul: fix csi node compatible Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 26/53] ARM: dts: imx6ul: fix lcdif " Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 27/53] ARM: dts: imx6ul: fix qspi " Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 28/53] ARM: dts: BCM5301X: Add DT for Meraki MR26 Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 29/53] ARM: dts: ux500: Fix Janice accelerometer mounting matrix Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 30/53] ARM: dts: ux500: Fix Codina " Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 31/53] ARM: dts: ux500: Fix Gavini " Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 32/53] arm64: dts: qcom: timer should use only 32-bit size Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 33/53] spi: synquacer: Add missing clk_disable_unprepare() Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 34/53] ARM: OMAP2+: display: Fix refcount leak bug Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 35/53] ARM: OMAP2+: pdata-quirks: " Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 36/53] ACPI: EC: Remove duplicate ThinkPad X1 Carbon 6th entry from DMI quirks Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 37/53] ACPI: EC: Drop the EC_FLAGS_IGNORE_DSDT_GPE quirk Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 38/53] ACPI: PM: save NVS memory for Lenovo G40-45 Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 39/53] ACPI: LPSS: Fix missing check in register_device_clock() Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 40/53] ARM: dts: qcom: sdx55: Fix the IRQ trigger type for UART Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 41/53] arm64: dts: qcom: add missing AOSS QMP compatible fallback Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 42/53] arm64: dts: qcom: ipq8074: fix NAND node name Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 43/53] arm64: dts: allwinner: a64: orangepi-win: Fix LED " Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 44/53] ARM: shmobile: rcar-gen2: Increase refcount for new reference Sasha Levin
2022-08-08  1:33   ` Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 45/53] firmware: tegra: Fix error check return value of debugfs_create_file() Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 46/53] hwmon: (dell-smm) Add Dell XPS 13 7390 to fan control whitelist Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 47/53] ACPI: video: Use native backlight on Dell Inspiron N4010 Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 48/53] hwmon: (sht15) Fix wrong assumptions in device remove callback Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 49/53] PM: hibernate: defer device probing when resuming from hibernation Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 50/53] selinux: fix memleak in security_read_state_kernel() Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 51/53] selinux: Add boundary check in put_entry() Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 52/53] skbuff: don't mix ubuf_info from different sources Sasha Levin
2022-08-08  1:33 ` [PATCH AUTOSEL 5.18 53/53] kasan: test: Silence GCC 12 warnings Sasha Levin

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