Sorry for the really long delay this time around. I am used to replying within a
day normally, and this time it just took so much time.
For next time please rebase on latest updates in pm/linux-next as there are
few updates there.
On 25 July 2014 06:37, Saravana Kannan <skannan@xxxxxxxxxxxxxx> wrote:
> There's no need to wait for the CPU going down to fully go offline to
> restart the governor. We can stop the governor, change policy->cpus and
> immediately restart the governor. This should reduce the time without any
> CPUfreq monitoring and also help future patches with simplifying the code.
I agree with the idea here, though the $subject can be improved a bit
here..
> Signed-off-by: Saravana Kannan <skannan@xxxxxxxxxxxxxx>
> ---
> drivers/cpufreq/cpufreq.c | 33 ++++++++++++++++++---------------
> 1 file changed, 18 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 62259d2..ee0eb7b 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1390,6 +1390,21 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
> cpufreq_driver->stop_cpu(policy);
> }
>
> + down_write(&policy->rwsem);
> + cpumask_clear_cpu(cpu, policy->cpus);
> + up_write(&policy->rwsem);
There is a down_read() present early in this routine and we better update this
at that place only.
> + if (cpus > 1 && has_target()) {
We already have a if (cpus > 1) block, move this there.
> + ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
> + if (!ret)
> + ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
> +
> + if (ret) {
> + pr_err("%s: Failed to start governor\n", __func__);
> + return ret;
> + }
> + }
> +
> return 0;
> }
>
> @@ -1410,15 +1425,12 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
> return -EINVAL;
> }
>
> - down_write(&policy->rwsem);
> + down_read(&policy->rwsem);
> cpus = cpumask_weight(policy->cpus);
> -
> - if (cpus > 1)
> - cpumask_clear_cpu(cpu, policy->cpus);
> - up_write(&policy->rwsem);
> + up_read(&policy->rwsem);
>
> /* If cpu is last user of policy, free policy */
> - if (cpus == 1) {
> + if (cpus == 0) {
> if (has_target()) {
> ret = __cpufreq_governor(policy,
> CPUFREQ_GOV_POLICY_EXIT);
> @@ -1447,15 +1459,6 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
>
> if (!cpufreq_suspended)
> cpufreq_policy_free(policy);
> - } else if (has_target()) {
> - ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
> - if (!ret)
> - ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
> -
> - if (ret) {
> - pr_err("%s: Failed to start governor\n", __func__);
> - return ret;
> - }
> }
Also, you must mention in the log about an important change you are making.
Don't know if there are any side effects...
You are emptying policy->cpus on removal of last CPU of a policy, which wasn't
the case earlier.
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