From: Sumit Gupta <sumitg@nvidia.com>
To: Beata Michalska <beata.michalska@arm.com>,
<linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>, <ionela.voinescu@arm.com>,
<vanshikonda@os.amperecomputing.com>
Cc: <sudeep.holla@arm.com>, <will@kernel.org>,
<catalin.marinas@arm.com>, <vincent.guittot@linaro.org>,
<yang@os.amperecomputing.com>, <lihuisong@huawei.com>,
linux-tegra <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH v4 3/4] arm64: Update AMU-based frequency scale factor on entering idle
Date: Thu, 11 Apr 2024 00:27:00 +0530 [thread overview]
Message-ID: <3ab3cbc1-234f-e0b6-4521-298018547aad@nvidia.com> (raw)
In-Reply-To: <20240405133319.859813-4-beata.michalska@arm.com>
Hi Beata,
This patch is giving abort due to 'amu_fie_cpus' mask which gets
allocated later in 'init_amu_fie()'.
] smp: Bringing up secondary CPUs ...
] Unable to handle kernel read from unreadable memory at virtual
address 0000000000000000
.......
] Call trace:
] arch_cpu_idle_enter+0x30/0xe0
] do_idle+0xb8/0x2e0
] cpu_startup_entry+0x3c/0x50
] rest_init+0x108/0x128
] start_kernel+0x7a4/0xa50
] __primary_switched+0x80/0x90
] Code: d53cd042 b8626800 f943c821 53067c02 (f8627821)
] ---[ end trace 0000000000000000 ]---
] Kernel panic - not syncing: Oops: Fatal exception
Added cpumask_available() check before access to fix.
+++ b/arch/arm64/kernel/topology.c
@@ -211,9 +211,13 @@ void arch_cpu_idle_enter(void)
{
unsigned int cpu = smp_processor_id();
- if (!cpumask_test_cpu(cpu, amu_fie_cpus))
+ if (cpumask_available(amu_fie_cpus) &&
+ !cpumask_test_cpu(cpu, amu_fie_cpus))
return;
Thank you,
Sumit Gupta
On 05/04/24 19:03, Beata Michalska wrote:
> External email: Use caution opening links or attachments
>
>
> Now that the frequency scale factor has been activated for retrieving
> current frequency on a given CPU, trigger its update upon entering
> idle. This will, to an extent, allow querying last known frequency
> in a non-invasive way. It will also improve the frequency scale factor
> accuracy when a CPU entering idle did not receive a tick for a while.
> As a consequence, for idle cores, the reported frequency will be the
> last one observed before entering the idle state.
>
> Suggested-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
> Signed-off-by: Beata Michalska <beata.michalska@arm.com>
> ---
> arch/arm64/kernel/topology.c | 17 +++++++++++++++--
> 1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index b03fe8617721..f204f6489f98 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
> @@ -207,6 +207,19 @@ static struct scale_freq_data amu_sfd = {
> .set_freq_scale = amu_scale_freq_tick,
> };
>
> +void arch_cpu_idle_enter(void)
> +{
> + unsigned int cpu = smp_processor_id();
> +
> + if (!cpumask_test_cpu(cpu, amu_fie_cpus))
> + return;
> +
> + /* Kick in AMU update but only if one has not happened already */
> + if (housekeeping_cpu(cpu, HK_TYPE_TICK) &&
> + time_is_before_jiffies(per_cpu(cpu_amu_samples.last_update, cpu)))
> + amu_scale_freq_tick();
> +}
> +
> #define AMU_SAMPLE_EXP_MS 20
>
> unsigned int arch_freq_get_on_cpu(int cpu)
> @@ -232,8 +245,8 @@ unsigned int arch_freq_get_on_cpu(int cpu)
> * this boils down to identifying an active cpu within the same freq
> * domain, if any.
> */
> - if (!housekeeping_cpu(cpu, HK_TYPE_TICK) ||
> - time_is_before_jiffies(last_update + msecs_to_jiffies(AMU_SAMPLE_EXP_MS))) {
> + if (!housekeeping_cpu(cpu, HK_TYPE_TICK) || (!idle_cpu(cpu) &&
> + time_is_before_jiffies(last_update + msecs_to_jiffies(AMU_SAMPLE_EXP_MS)))) {
> struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> int ref_cpu = cpu;
>
> --
> 2.25.1
>
next parent reply other threads:[~2024-04-10 18:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240405133319.859813-1-beata.michalska@arm.com>
[not found] ` <20240405133319.859813-4-beata.michalska@arm.com>
2024-04-10 18:57 ` Sumit Gupta [this message]
2024-04-11 19:30 ` [PATCH v4 3/4] arm64: Update AMU-based frequency scale factor on entering idle Beata Michalska
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