On 08/07/2014 01:54 AM, Viresh Kumar wrote:
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.
Will do.
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..
Suggestions welcome. I think the current one explains the main point of
this change.
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.
I would rather not. My v1 patch series was super refactored to allow a
lot of reuse, etc. But you guys complained about the diffs being
confusing (which was a valid point).
Also, if we are talking about refactoring this, there's room for much
better refactor at the end of the series. I will add a patch to the
series to do the refactoring.
+ if (cpus > 1 && has_target()) {
We already have a if (cpus > 1) block, move this there.
That only runs if cpu != policy->cpu. This needs to run irrespective of
that.
+ 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.
You mean the log in the cover letter? Will do.
-Saravana
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