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SubjectRe: [PATCH] arm64: Demote boot and shutdown messages to pr_debug
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On 01/05/2019 11:47, Mark Rutland wrote:
> On Tue, Apr 30, 2019 at 03:38:31PM -0700, Florian Fainelli wrote:
>> Similar to commits c68b0274fb3cf ("ARM: reduce "Booted secondary
>> processor" message to debug level") and 035e787543de7 ("ARM: 8644/1: Reduce "CPU:
>> shutdown" message to debug level"), demote the secondary_start_kernel()
>> and __cpu_die() messages from info, respectively notice to debug. While
>> we are at it, also do this for cpu_psci_cpu_kill() which is redundant
>> with __cpu_die().
>>
>> This helps improve the amount of possible hotplug cycles by around +50%
>> on ARCH_BRCMSTB.
>
> Could you elaborate on why that matters?

Yeah, in general if you have a slow serial console then removing all the
prints from the kernel makes lots of things much faster, but that's not
necessarily a good argument for doing so. If that's a problem that
really concerns users then I'd have to ask why they aren't using a
stricter loglevel or a different console to begin with.

> e.g. is this just for testing, or does this matter in some shutdown or
> hibernate scenario?
>
>> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
>> ---
>> arch/arm64/kernel/psci.c | 2 +-
>> arch/arm64/kernel/smp.c | 4 ++--
>> 2 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
>> index 8cdaf25e99cd..a78581046c80 100644
>> --- a/arch/arm64/kernel/psci.c
>> +++ b/arch/arm64/kernel/psci.c
>> @@ -96,7 +96,7 @@ static int cpu_psci_cpu_kill(unsigned int cpu)
>> for (i = 0; i < 10; i++) {
>> err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
>> if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
>> - pr_info("CPU%d killed.\n", cpu);
>> + pr_debug("CPU%d killed.\n", cpu);
>> return 0;
>> }
>>
>> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
>> index 824de7038967..71fd2b5a3f0e 100644
>> --- a/arch/arm64/kernel/smp.c
>> +++ b/arch/arm64/kernel/smp.c
>> @@ -259,7 +259,7 @@ asmlinkage notrace void secondary_start_kernel(void)
>> * the CPU migration code to notice that the CPU is online
>> * before we continue.
>> */
>> - pr_info("CPU%u: Booted secondary processor 0x%010lx [0x%08x]\n",
>> + pr_debug("CPU%u: Booted secondary processor 0x%010lx [0x%08x]\n",
>> cpu, (unsigned long)mpidr,
>> read_cpuid_id());
>
> I generally agree that we don't need to be verbose, and demoting these
> to debug is fine, but it's a shame that these won't be accessible in
> defconfig.
>
> I wonder if we should enable DYNAMIC_DEBUG so that we can turn these on
> from the kernel command line, or if we should have something like a
> verbose_hotplug option specifically for these messages.

We've had DYNAMIC_DEBUG=y in defconfig for a while already :/

Robin.

>
> Thanks,
> Mark.
>
>> update_cpu_boot_status(CPU_BOOT_SUCCESS);
>> @@ -348,7 +348,7 @@ void __cpu_die(unsigned int cpu)
>> pr_crit("CPU%u: cpu didn't die\n", cpu);
>> return;
>> }
>> - pr_notice("CPU%u: shutdown\n", cpu);
>> + pr_debug("CPU%u: shutdown\n", cpu);
>>
>> /*
>> * Now that the dying CPU is beyond the point of no return w.r.t.
>> --
>> 2.17.1
>>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>

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