Hi Viresh, On 12/12/17 17:07, Viresh Kumar wrote:
[...] > From: Viresh Kumar <viresh.ku...@linaro.org> > Date: Tue, 12 Dec 2017 15:43:26 +0530 > Subject: [PATCH] sched: Keep track of cpufreq utilization update flags > > Currently the schedutil governor overwrites the sg_cpu->flags field on > every call to the utilization handler. It was pretty good as the initial > implementation of utilization handlers, there are several drawbacks > though. > > The biggest drawback is that the sg_cpu->flags field doesn't always > represent the correct type of tasks that are enqueued on a CPU's rq. For > example, if a fair task is enqueued while a RT or DL task is running, we > will overwrite the flags with value 0 and that may take the CPU to lower > OPPs unintentionally. There can be other corner cases as well which we > aren't aware of currently. > > This patch changes the current implementation to keep track of all the > task types that are currently enqueued to the CPUs rq. There are two > flags for every scheduling class now, one to set the flag and other one > to clear it. The flag is set by the scheduling classes from the existing > set of calls to cpufreq_update_util(), and the flag is cleared when the > last task of the scheduling class is dequeued. For now, the util update > handlers return immediately if they were called to clear the flag. > > We can add more optimizations over this patch separately. > > The last parameter of sugov_set_iowait_boost() is also dropped as the > function can get it from sg_cpu anyway. > > Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org> [...] > @@ -655,7 +669,7 @@ static int sugov_start(struct cpufreq_policy *policy) > memset(sg_cpu, 0, sizeof(*sg_cpu)); > sg_cpu->cpu = cpu; > sg_cpu->sg_policy = sg_policy; > - sg_cpu->flags = SCHED_CPUFREQ_RT; > + sg_cpu->flags = 0; > sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq; > } Why this change during initialization? Thanks, - Juri