Re: [PATCH V2 00/20] cpufreq: Don't loose cpufreq history on CPU hotplug

[Saravana Kannan <skannan@codeaurora.org>]

On 02/19/2015 03:32 AM, Viresh Kumar wrote:
> Hi Rafael,
>
> The aim of this series is to stop managing cpufreq sysfs directories on CPU
> hotplugs.
>
> Currently on removal of a 'cpu != policy->cpu', we remove its sysfs directories
> by removing the soft-link. And on removal of policy->cpu, we migrate the sysfs
> directories to the next cpu. But if policy->cpu was the last CPU, we remove the
> policy completely and allocate it again as soon as the CPUs come back. This has
> shortcomings:
>
> - Code Complexity
> - Slower hotplug
> - sysfs file permissions are reset after all policy->cpus are offlined
> - CPUFreq stats history lost after all policy->cpus are offlined
> - Special management of sysfs stuff during suspend/resume
>
>
> To make things simple we stop playing with sysfs files unless the driver is
> getting removed. Also the policy is kept intact to be used later.
>
> First few patches provide a clean base for others *more important* patches.
>
> Rebased-over: your bleeding edge branch as there were dependencies on my earlier
> patches.
>
> Pushed here:
>
> git://git.linaro.org/people/viresh.kumar/linux.git cpufreq/core/sysfs
>
> v1->V2:
> - Dropped the idea of using policy-lists for getting policy for any cpu
> - Also dropped fallback list and its per-cpu variable
> - Stopped cleaning cpufreq_cpu_data and doing list_del(policy) on logical
>    hotplug.
> - Added support for physical hotplug of CPUs (Untested).
>
> @Srivatsa: Can you please have a look at the above change? I have cc'd you only
> on this one.
>
> Saravana Kannan (1):
>    cpufreq: Track cpu managing sysfs kobjects separately
>
> Cc: Srivatsa Bhat <srivatsa@mit.edu>
>
> Viresh Kumar (19):
>    cpufreq: Add doc style comment about cpufreq_cpu_{get|put}()
>    cpufreq: Merge __cpufreq_add_dev() and cpufreq_add_dev()
>    cpufreq: Throw warning when we try to get policy for an invalid CPU
>    cpufreq: Keep a single path for adding managed CPUs
>    cpufreq: Clear policy->cpus even for the last CPU
>    cpufreq: Create for_each_{in}active_policy()
>    cpufreq: Call schedule_work() for the last active policy
>    cpufreq: Don't clear cpufreq_cpu_data and policy list for inactive
>      policies
>    cpufreq: Get rid of cpufreq_cpu_data_fallback
>    cpufreq: Don't traverse list of all policies for adding policy for a
>      cpu
>    cpufreq: Manage governor usage history with 'policy->last_governor'
>    cpufreq: Mark policy->governor = NULL for inactive policies
>    cpufreq: Don't allow updating inactive-policies from sysfs
>    cpufreq: Stop migrating sysfs files on hotplug
>    cpufreq: Remove cpufreq_update_policy()
>    cpufreq: Initialize policy->kobj while allocating policy
>    cpufreq: Call cpufreq_policy_put_kobj() from cpufreq_policy_free()
>    cpufreq: Restart governor as soon as possible
>    cpufreq: Add support for physical hoplug of CPUs
>
>   drivers/cpufreq/cpufreq.c | 593 ++++++++++++++++++++++++++--------------------
>   include/linux/cpufreq.h   |   5 +-
>   2 files changed, 340 insertions(+), 258 deletions(-)
>

Just so it's clear I'm looking at these patches, I'm acking each patch 
as and when I look at them.

I might come back and nack some of them if I find an issue with patch N 
while looking at patch N + M. When I ack the last patch in the series, 
all my previous acks can be considered as final as they can be.

-Saravana

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