From: Wyes Karny <wyes.karny(a)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(a)amd.com>
Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com>
Tested-by: Zhang Rui <rui.zhang(a)intel.com>
Link: https://lkml.kernel.org/r/fdc2dc2d0a1bc21c2f53d989ea2d2ee3ccbc0dbe.16545383…
Signed-off-by: Sasha Levin <sashal(a)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 d456ce21c255..9346c95e8879 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -821,6 +821,10 @@ 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
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Hi Greg and Sasha,
This two patches are backports for stable branchs from v4.9 to v5.4.
These two patches are reducing the chance of destructive RMW cycle,
where btrfs can use corrupted data to generate new P/Q, thus making some
repairable data unrepairable.
Those patches are more important than what I initially thought, thus
unfortunately they are not CCed to stable by themselves.
Furthermore due to recent refactors/renames, there are quite some member
change related to those patches, thus have to be manually backported.
One of the fastest way to verify the behavior is the existing btrfs/125
test case from fstests. (not in auto group AFAIK).
Qu Wenruo (2):
btrfs: only write the sectors in the vertical stripe which has data
stripes
btrfs: raid56: don't trust any cached sector in
__raid56_parity_recover()
fs/btrfs/raid56.c | 74 ++++++++++++++++++++++++++++++++++++-----------
1 file changed, 57 insertions(+), 17 deletions(-)
--
2.37.0
--
Congratulation! Your delayed payment has been released this morning.
Kindly reconfirm your details for payment to you.
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Barclays Bank Plc,
Registered number: 1026167,
1 Churchill Place, London, ENG E14 5HP,
SWIFT Code: BARCGB21,
Direct Telephone: +44 770 000 8965,
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