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arm64: add hw_nmi_get_sample_period for preparation of lockup detector

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Set safe maximum CPU frequency to 5 GHz in case a particular platform
doesn't implement cpufreq driver.  Although, architecture doesn't put any
restrictions on maximum frequency but 5 GHz seems to be safe maximum given
the available Arm CPUs in the market which are clocked much less than 5
GHz.

On the other hand, we can't make it much higher as it would lead to a
large hard-lockup detection timeout on parts which are running slower (eg.
1GHz on Developerbox) and doesn't possess a cpufreq driver.

Link: https://lkml.kernel.org/r/20230519101840.v5.17.Ia9d02578e89c3f44d3cb12eec8b0176603c8ab2f@changeid
Co-developed-by: Sumit Garg <[email protected]>
Signed-off-by: Sumit Garg <[email protected]>
Co-developed-by: Pingfan Liu <[email protected]>
Signed-off-by: Pingfan Liu <[email protected]>
Signed-off-by: Lecopzer Chen <[email protected]>
Signed-off-by: Douglas Anderson <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Chen-Yu Tsai <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Colin Cross <[email protected]>
Cc: Daniel Thompson <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Masayoshi Mizuma <[email protected]>
Cc: Matthias Kaehlcke <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: "Ravi V. Shankar" <[email protected]>
Cc: Ricardo Neri <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: Tzung-Bi Shih <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
This commit is contained in:
Lecopzer Chen
2023-06-09 17:44:21 -07:00
committed by Andrew Morton
parent 930d8f8dba
commit 94946f9eaa
2 changed files with 25 additions and 0 deletions
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arch/arm64/kernel/Makefile
+1
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@@ -45,6 +45,7 @@ obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o entry-ftrace.o
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_ARM64_MODULE_PLTS) += module-plts.o
obj-$(CONFIG_PERF_EVENTS) += perf_regs.o perf_callchain.o
obj-$(CONFIG_HARDLOCKUP_DETECTOR_PERF) += watchdog_hld.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
obj-$(CONFIG_CPU_PM) += sleep.o suspend.o
obj-$(CONFIG_CPU_IDLE) += cpuidle.o
arch/arm64/kernel/watchdog_hld.c
+24
View File
@@ -0,0 +1,24 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/cpufreq.h>
/*
* Safe maximum CPU frequency in case a particular platform doesn't implement
* cpufreq driver. Although, architecture doesn't put any restrictions on
* maximum frequency but 5 GHz seems to be safe maximum given the available
* Arm CPUs in the market which are clocked much less than 5 GHz. On the other
* hand, we can't make it much higher as it would lead to a large hard-lockup
* detection timeout on parts which are running slower (eg. 1GHz on
* Developerbox) and doesn't possess a cpufreq driver.
*/
#define SAFE_MAX_CPU_FREQ 5000000000UL // 5 GHz
u64 hw_nmi_get_sample_period(int watchdog_thresh)
{
unsigned int cpu = smp_processor_id();
unsigned long max_cpu_freq;
max_cpu_freq = cpufreq_get_hw_max_freq(cpu) * 1000UL;
if (!max_cpu_freq)
max_cpu_freq = SAFE_MAX_CPU_FREQ;
return (u64)max_cpu_freq * watchdog_thresh;
}