From: Valentin Schneider <valentin.schneider@arm.com>
To: Suzuki Kuruppassery Poulose <suzuki.poulose@arm.com>,
Ionela Voinescu <ionela.voinescu@arm.com>,
catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com,
maz@kernel.org, sudeep.holla@arm.com, lukasz.luba@arm.com,
rjw@rjwysocki.net
Cc: peterz@infradead.org, mingo@redhat.com,
vincent.guittot@linaro.org, viresh.kumar@linaro.org,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH v3 1/7] arm64: add support for the AMU extension v1
Date: Wed, 12 Feb 2020 14:54:45 +0000 [thread overview]
Message-ID: <b2b640ac-0cc3-b09e-1f6c-f01234295b3b@arm.com> (raw)
In-Reply-To: <93472f17-6465-641d-ea82-3230b5697ffd@arm.com>
On 12/02/2020 11:30, Suzuki Kuruppassery Poulose wrote:
>> +static bool has_amu(const struct arm64_cpu_capabilities *cap,
>> + int __unused)
>> +{
>> + /*
>> + * The AMU extension is a non-conflicting feature: the kernel can
>> + * safely run a mix of CPUs with and without support for the
>> + * activity monitors extension. Therefore, if not disabled through
>> + * the kernel command line early parameter, enable the capability
>> + * to allow any late CPU to use the feature.
>> + *
>> + * With this feature enabled, the cpu_enable function will be called
>> + * for all CPUs that match the criteria, including secondary and
>> + * hotplugged, marking this feature as present on that respective CPU.
>> + * The enable function will also print a detection message.
>> + */
>> +
>> + if (!disable_amu && !zalloc_cpumask_var(&amu_cpus, GFP_KERNEL)) {
>
> This looks problematic. Don't we end up in allocating the memory during
> "each CPU" check and thus leaking memory ? Do we really need to allocate
> this dynamically ?
>
For the static vs dynamic thing, I think it's not *too* important here since
we don't risk pwning the stack because of the cpumask. That said, if we are
somewhat pedantic about memory usage, the static allocation is done
against NR_CPUS whereas the dynamic one is done against nr_cpu_ids.
Pretty inconsequential for a single cpumask, but I guess it all adds up
eventually...
next prev parent reply other threads:[~2020-02-12 14:54 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 18:45 [PATCH v3 0/7] arm64: ARMv8.4 Activity Monitors support Ionela Voinescu
2020-02-11 18:45 ` [PATCH v3 1/7] arm64: add support for the AMU extension v1 Ionela Voinescu
2020-02-12 11:30 ` Suzuki Kuruppassery Poulose
2020-02-12 14:54 ` Valentin Schneider [this message]
2020-02-12 16:10 ` Ionela Voinescu
2020-02-12 16:20 ` Suzuki Kuruppassery Poulose
2020-02-12 18:20 ` Ionela Voinescu
2020-02-12 19:24 ` Suzuki K Poulose
2020-02-12 20:19 ` Ionela Voinescu
2020-02-12 16:24 ` Vladimir Murzin
2020-02-12 18:27 ` Ionela Voinescu
2020-02-11 18:45 ` [PATCH v3 2/7] arm64: trap to EL1 accesses to AMU counters from EL0 Ionela Voinescu
2020-02-12 11:44 ` Suzuki Kuruppassery Poulose
2020-02-12 15:36 ` Valentin Schneider
2020-02-11 18:45 ` [PATCH v3 3/7] arm64/kvm: disable access to AMU registers from kvm guests Ionela Voinescu
2020-02-12 15:36 ` Valentin Schneider
2020-02-12 16:33 ` Suzuki Kuruppassery Poulose
2020-02-11 18:45 ` [PATCH v3 4/7] Documentation: arm64: document support for the AMU extension Ionela Voinescu
2020-02-12 15:36 ` Valentin Schneider
2020-02-11 18:45 ` [PATCH v3 5/7] cpufreq: add function to get the hardware max frequency Ionela Voinescu
2020-02-12 4:14 ` Viresh Kumar
2020-02-13 11:59 ` Valentin Schneider
2020-02-13 12:59 ` Ionela Voinescu
2020-02-13 15:22 ` Valentin Schneider
2020-02-11 18:45 ` [PATCH v3 6/7] arm64: use activity monitors for frequency invariance Ionela Voinescu
2020-02-12 18:59 ` Lukasz Luba
2020-02-13 9:47 ` Ionela Voinescu
2020-02-17 16:59 ` Valentin Schneider
2020-02-23 18:49 ` Ionela Voinescu
2020-02-11 18:45 ` [PATCH v3 7/7] clocksource/drivers/arm_arch_timer: validate arch_timer_rate Ionela Voinescu
2020-02-12 9:30 ` Valentin Schneider
2020-02-12 10:32 ` Ionela Voinescu
2020-02-12 10:01 ` Lukasz Luba
2020-02-12 10:12 ` Marc Zyngier
2020-02-12 10:54 ` Ionela Voinescu
2020-02-12 10:55 ` Lukasz Luba
2020-02-12 11:10 ` Marc Zyngier
2020-02-12 11:43 ` Lukasz Luba
2020-02-12 11:12 ` Valentin Schneider
2020-02-14 0:35 ` Thomas Gleixner
2020-02-14 15:45 ` Ionela Voinescu
2020-02-14 15:57 ` Ionela Voinescu
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