[PATCH v2 0/10] cpufreq: governor: ondemand/conservative data structures rework

[Rafael J. Wysocki]

On Thursday, February 04, 2016 12:12:52 AM Rafael J. Wysocki wrote:
> Hi,
> 
> A few days ago I looked at the common code used by the ondemand and conservative
> governors because of the deadlock issue that Viresh has addressed recently
> (http://marc.info/?l=linux-pm&m=145450832814058&w=4) and it occurred to me
> that the whole thing was really too tangled and might be made easier to follow
> at least.  I started to work on this and ended up with the following series.
> 
> I'm not really going to stop here, but first, I'd like to let everybody know
> that this is happening and second, I'll need to rebase these patches on the
> ones from Viresh (in the series linked above), but that may take some time
> and I don't want to sit on them for all that long.
> 
> Overall, I'd like the governor code to be cleaner and easier to follow, so we can
> move at least some parts of governor work to utilization update callbacks (invoked
> by the scheduler) or to at least to irq_work so as to reduce the usage of process
> context in cpufreq to absolute minimum.  That's the plan for the future, but for
> now this is just a major cleanup.
> 
> [1/11] Clean up the way in which the default and fallback governors are set up.
> [2/11] Use a common global mutex for dbs_data protection.
> [3/11] Use common global pointer to dbs_data for system-wide governors.
> [4/11] Avoid passing dbs_data pointers to functions that can get them by themselves.
> [5/11] Make struct governor be a member of struct common_dbs_data.
> [6/11] Rename struct common_dbs_data to struct dbs_governor.
> [7/11] Rework cpufreq_governor_dbs() so it can be used as a governor callback directly.
> [8/11] Drop the dbs_governor (former cdata) pointer from struct dbs_data.
> [9/11] Rename struct cpu_common_dbs_info to struct policy_dbs_info.
> [10/11] Rearrange data structures so policy->governor_data points to struct policy_dbs_info.
> [11/11] Drop the second argument of dbs_check_cpu().
> 
> The patches are on top of 4.5-rc2 with my earlier series replacing timers with
> utilization update callbacks (http://marc.info/?l=linux-kernel&m=145410842801883&w=4)
> applied.

Some bugs fixed, some comments addressed.  It's time for a v2. :-)

The most significant difference from the previous one is that I've dropped patch
[3/11] (so there are 10 of them in the series now) due to a problem with it pointed
out by Viresh.  Fortunately, this particular one was completely not essential and
the dependencies on it were rather cosmetic.

In addition to that I've rebased the series on top of
https://patchwork.kernel.org/patch/8229901/ as that differs from its previous
version quite a bit.

I've already queued up [1/10] for 4.6 as it seems totally uncontroversial.

The whole series (along with some patches it depends on) is available from the
git branch at

git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git pm-cpufreq-rjw

in case someone wants to try it.  I've tested it (very lightly) on an x86 laptop
with the ACPI cpufreq driver and the ondemand governor.

Thanks,
Rafael