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Groups > linux.kernel > #1324259
| From | "Rafael J. Wysocki" <rafael@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops |
| Date | 2016-02-02 17:40 +0100 |
| Message-ID | <qXM9J-5Km-11@gated-at.bofh.it> (permalink) |
| References | <qXGQG-1uV-11@gated-at.bofh.it> <qXGQI-1uV-51@gated-at.bofh.it> <qXLnk-55B-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Feb 2, 2016 at 4:47 PM, Juri Lelli <juri.lelli@arm.com> wrote:
> Hi Viresh,
>
> On 02/02/16 16:27, Viresh Kumar wrote:
>> Until now, governors (ondemand/conservative) were using the
>> 'global-attr' or 'freq-attr', depending on the sysfs location where we
>> want to create governor's directory.
>>
>> The problem is that, in case of 'freq-attr', we are forced to use
>> show()/store() present in cpufreq.c, which always take policy->rwsem.
>>
>> And because of that we were facing some ABBA lockups during governor
>> callback event CPUFREQ_GOV_POLICY_EXIT. And so we were dropping the
>> rwsem right before calling governor callback for CPUFREQ_GOV_POLICY_EXIT
>> event.
>>
>> That caused further problems and it never worked perfectly.
>>
>> This patch attempts to fix that by creating separate sysfs-ops for
>> cpufreq governors.
>>
>> Because things got much simplified now, we don't need separate
>> show/store callbacks for governor-for-system and governor-per-policy
>> cases.
>>
>> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
>
> This patch cleans things up a lot, that's good.
>
> One thing I'm still concerned about, though: don't we need some locking
> in place for some of the store operations on governors attributes? Are
> store_{ignore_nice_load, sampling_down_fact, etc} safe without locking?
That would require some investigation I suppose.
> It seems that we can call them from different cpus concurrently.
Yes, we can.
One quick-and-dirty way of dealing with that might be to introduce a
"sysfs lock" into struct dbs_data and hold that around the invocation
of gattr->store() in the sysfs_ops's ->store callback.
>
> Best,
>
> - Juri
BTW, you could have dropped the stuff below this line from your reply
message. That at least would have prevented tools like Patchwork from
storing useless garbage.
Thanks,
Rafael
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH 0/5] cpufreq: governors: Solve the ABBA lockups Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-02 12:00 +0100
[PATCH 3/5] cpufreq: governor: Remove unused sysfs attribute macros Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-02 12:00 +0100
Re: [PATCH 3/5] cpufreq: governor: Remove unused sysfs attribute macros "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-02 22:40 +0100
[PATCH 4/5] cpufreq: Don't drop rwsem before calling CPUFREQ_GOV_POLICY_EXIT Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-02 12:00 +0100
Re: [PATCH 4/5] cpufreq: Don't drop rwsem before calling CPUFREQ_GOV_POLICY_EXIT "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-02 23:00 +0100
Re: [PATCH 4/5] cpufreq: Don't drop rwsem before calling CPUFREQ_GOV_POLICY_EXIT Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 07:00 +0100
Re: [PATCH 4/5] cpufreq: Don't drop rwsem before calling CPUFREQ_GOV_POLICY_EXIT "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-03 13:30 +0100
Re: [PATCH 4/5] cpufreq: Don't drop rwsem before calling CPUFREQ_GOV_POLICY_EXIT Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 14:10 +0100
[PATCH 5/5] cpufreq: Get rid of ->governor_enabled and its lock Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-02 12:00 +0100
Re: [PATCH 5/5] cpufreq: Get rid of ->governor_enabled and its lock Juri Lelli <juri.lelli@arm.com> - 2016-02-02 17:50 +0100
Re: [PATCH 5/5] cpufreq: Get rid of ->governor_enabled and its lock Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 07:10 +0100
Re: [PATCH 5/5] cpufreq: Get rid of ->governor_enabled and its lock Juri Lelli <juri.lelli@arm.com> - 2016-02-03 12:10 +0100
Re: [PATCH 5/5] cpufreq: Get rid of ->governor_enabled and its lock Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 12:10 +0100
Re: [PATCH 5/5] cpufreq: Get rid of ->governor_enabled and its lock "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-02 23:00 +0100
[PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-02 12:00 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Juri Lelli <juri.lelli@arm.com> - 2016-02-02 16:50 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-02 17:40 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Juri Lelli <juri.lelli@arm.com> - 2016-02-02 18:10 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-02 20:50 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Saravana Kannan <skannan@codeaurora.org> - 2016-02-02 23:30 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-03 00:50 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-03 02:10 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Saravana Kannan <skannan@codeaurora.org> - 2016-02-03 02:40 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-03 03:00 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Saravana Kannan <skannan@codeaurora.org> - 2016-02-03 05:10 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 08:00 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Saravana Kannan <skannan@codeaurora.org> - 2016-02-03 21:10 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 08:00 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Juri Lelli <juri.lelli@arm.com> - 2016-02-03 12:00 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 12:00 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Saravana Kannan <skannan@codeaurora.org> - 2016-02-03 21:20 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 08:00 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 07:40 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-02 22:30 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 08:00 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-03 13:50 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 14:30 +0100
Re: [PATCH 2/5] cpufreq: governor: Create separate sysfs-ops "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-03 14:40 +0100
Re: [PATCH 0/5] cpufreq: governors: Solve the ABBA lockups Juri Lelli <juri.lelli@arm.com> - 2016-02-02 12:30 +0100
Re: [PATCH 0/5] cpufreq: governors: Solve the ABBA lockups "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-02 21:10 +0100
Re: [PATCH 0/5] cpufreq: governors: Solve the ABBA lockups Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 03:30 +0100
Re: [PATCH 0/5] cpufreq: governors: Solve the ABBA lockups Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-03 12:40 +0100
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