From: Viresh Kumar <viresh.kumar@linaro.org>
To: morten.rasmussen@arm.com
Cc: paulmck@linux.vnet.ibm.com, pjt@google.com, peterz@infradead.org,
suresh.b.siddha@intel.com, linaro-sched-sig@lists.linaro.org,
linaro-dev@lists.linaro.org, linux-kernel@vger.kernel.org,
Arvind.Chauhan@arm.com, Amit Kucheria <amit.kucheria@linaro.org>,
Robin Randhawa <robin.randhawa@arm.com>
Subject: Re: [RFC PATCH 06/10] ARM: sched: Use device-tree to provide fast/slow CPU list for HMP
Date: Thu, 4 Oct 2012 12:19:32 +0530 [thread overview]
Message-ID: <CAKohponvN+-rBxeBW6L1UiwzuDLJ+zymzawyoT3PdxMB31vxRw@mail.gmail.com> (raw)
In-Reply-To: <1348252345-5642-7-git-send-email-morten.rasmussen@arm.com>
On 22 September 2012 00:02, <morten.rasmussen@arm.com> wrote:
> From: Morten Rasmussen <morten.rasmussen@arm.com>
>
> We can't rely on Kconfig options to set the fast and slow CPU lists for
> HMP scheduling if we want a single kernel binary to support multiple
> devices with different CPU topology. E.g. TC2 (ARM's Test-Chip-2
> big.LITTLE system), Fast Models, or even non big.LITTLE devices.
>
> This patch adds the function arch_get_fast_and_slow_cpus() to generate
> the lists at run-time by parsing the CPU nodes in device-tree; it
> assumes slow cores are A7s and everything else is fast. The function
> still supports the old Kconfig options as this is useful for testing the
> HMP scheduler on devices without big.LITTLE.
But this code is handling this case too at the end, with following logic:
> + cpumask_setall(fast);
> + cpumask_clear(slow);
Am i missing something?
> This patch is reuse of a patch by Jon Medhurst <tixy@linaro.org> with a
> few bits left out.
Then probably he must be the author of this commit? Also a SOB is required
from him here.
> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
> ---
> arch/arm/Kconfig | 4 ++-
> arch/arm/kernel/topology.c | 69 ++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 72 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index cb80846..f1271bc 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1588,13 +1588,15 @@ config HMP_FAST_CPU_MASK
> string "HMP scheduler fast CPU mask"
> depends on SCHED_HMP
> help
> - Specify the cpuids of the fast CPUs in the system as a list string,
> + Leave empty to use device tree information.
> + Specify the cpuids of the fast CPUs in the system as a list string,
> e.g. cpuid 0+1 should be specified as 0-1.
>
> config HMP_SLOW_CPU_MASK
> string "HMP scheduler slow CPU mask"
> depends on SCHED_HMP
> help
> + Leave empty to use device tree information.
> Specify the cpuids of the slow CPUs in the system as a list string,
> e.g. cpuid 0+1 should be specified as 0-1.
>
> diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
> index 26c12c6..7682e12 100644
> --- a/arch/arm/kernel/topology.c
> +++ b/arch/arm/kernel/topology.c
> @@ -317,6 +317,75 @@ void store_cpu_topology(unsigned int cpuid)
> cpu_topology[cpuid].socket_id, mpidr);
> }
>
> +
> +#ifdef CONFIG_SCHED_HMP
> +
> +static const char * const little_cores[] = {
> + "arm,cortex-a7",
> + NULL,
> +};
> +
> +static bool is_little_cpu(struct device_node *cn)
> +{
> + const char * const *lc;
> + for (lc = little_cores; *lc; lc++)
> + if (of_device_is_compatible(cn, *lc))
> + return true;
> + return false;
> +}
> +
> +void __init arch_get_fast_and_slow_cpus(struct cpumask *fast,
> + struct cpumask *slow)
> +{
> + struct device_node *cn = NULL;
> + int cpu = 0;
> +
> + cpumask_clear(fast);
> + cpumask_clear(slow);
> +
> + /*
> + * Use the config options if they are given. This helps testing
> + * HMP scheduling on systems without a big.LITTLE architecture.
> + */
> + if (strlen(CONFIG_HMP_FAST_CPU_MASK) && strlen(CONFIG_HMP_SLOW_CPU_MASK)) {
> + if (cpulist_parse(CONFIG_HMP_FAST_CPU_MASK, fast))
> + WARN(1, "Failed to parse HMP fast cpu mask!\n");
> + if (cpulist_parse(CONFIG_HMP_SLOW_CPU_MASK, slow))
> + WARN(1, "Failed to parse HMP slow cpu mask!\n");
> + return;
> + }
> +
> + /*
> + * Else, parse device tree for little cores.
> + */
> + while ((cn = of_find_node_by_type(cn, "cpu"))) {
> +
> + if (cpu >= num_possible_cpus())
> + break;
> +
> + if (is_little_cpu(cn))
> + cpumask_set_cpu(cpu, slow);
> + else
> + cpumask_set_cpu(cpu, fast);
> +
> + cpu++;
> + }
> +
> + if (!cpumask_empty(fast) && !cpumask_empty(slow))
> + return;
> +
> + /*
> + * We didn't find both big and little cores so let's call all cores
> + * fast as this will keep the system running, with all cores being
> + * treated equal.
> + */
> + cpumask_setall(fast);
> + cpumask_clear(slow);
> +}
> +
> +#endif /* CONFIG_SCHED_HMP */
All above calls to of_*() routines have dependency on CONFIG_OF
--
viresh
next prev parent reply other threads:[~2012-10-04 6:49 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-21 18:32 [RFC PATCH 00/10] sched: Task placement for heterogeneous MP systems morten.rasmussen
2012-09-21 18:32 ` [RFC PATCH 01/10] sched: entity load-tracking load_avg_ratio morten.rasmussen
2012-09-21 18:32 ` [RFC PATCH 02/10] sched: Task placement for heterogeneous systems based on task load-tracking morten.rasmussen
2012-10-04 6:02 ` Viresh Kumar
2012-10-04 6:54 ` Amit Kucheria
2012-10-09 15:56 ` Morten Rasmussen
2012-10-09 16:58 ` Viresh Kumar
2012-09-21 18:32 ` [RFC PATCH 03/10] sched: Forced task migration on heterogeneous systems morten.rasmussen
2012-10-04 6:18 ` Viresh Kumar
2012-09-21 18:32 ` [RFC PATCH 04/10] sched: Introduce priority-based task migration filter morten.rasmussen
2012-10-04 4:37 ` Viresh Kumar
2012-10-04 6:27 ` Viresh Kumar
2012-10-09 16:40 ` Morten Rasmussen
2012-10-24 2:32 ` li guang
2012-09-21 18:32 ` [RFC PATCH 05/10] ARM: Add HMP scheduling support for ARM architecture morten.rasmussen
2012-09-21 18:32 ` [RFC PATCH 06/10] ARM: sched: Use device-tree to provide fast/slow CPU list for HMP morten.rasmussen
2012-10-04 6:49 ` Viresh Kumar [this message]
2012-10-10 10:17 ` Morten Rasmussen
2012-10-10 10:33 ` Viresh Kumar
2012-10-10 11:04 ` Morten Rasmussen
2012-10-10 11:29 ` Jon Medhurst (Tixy)
2012-09-21 18:32 ` [RFC PATCH 07/10] ARM: sched: Setup SCHED_HMP domains morten.rasmussen
2012-10-04 6:58 ` Viresh Kumar
2012-10-10 13:29 ` Morten Rasmussen
2012-09-21 18:32 ` [RFC PATCH 08/10] sched: Add ftrace events for entity load-tracking morten.rasmussen
2012-09-21 18:32 ` [RFC PATCH 09/10] sched: Add HMP task migration ftrace event morten.rasmussen
2012-09-21 18:32 ` [RFC PATCH 10/10] sched: SCHED_HMP multi-domain task migration control morten.rasmussen
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