From: Peter Zijlstra <peterz@infradead.org>
To: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
linux-api@vger.kernel.org, cgroups@vger.kernel.org,
Ingo Molnar <mingo@redhat.com>, Tejun Heo <tj@kernel.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Paul Turner <pjt@google.com>, Michal Koutny <mkoutny@suse.com>,
Quentin Perret <quentin.perret@arm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Juri Lelli <juri.lelli@redhat.com>, Todd Kjos <tkjos@google.com>,
Joel Fernandes <joelaf@google.com>,
Steve Muckle <smuckle@google.com>,
Suren Baghdasaryan <surenb@google.com>,
Alessio Balsini <balsini@android.com>
Subject: Re: [PATCH v14 1/6] sched/core: uclamp: Extend CPU's cgroup controller
Date: Fri, 30 Aug 2019 11:45:05 +0200 [thread overview]
Message-ID: <20190830094505.GA2369@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190822132811.31294-2-patrick.bellasi@arm.com>
On Thu, Aug 22, 2019 at 02:28:06PM +0100, Patrick Bellasi wrote:
> +#define _POW10(exp) ((unsigned int)1e##exp)
> +#define POW10(exp) _POW10(exp)
What is this magic? You're forcing a float literal into an integer.
Surely that deserves a comment!
> +struct uclamp_request {
> +#define UCLAMP_PERCENT_SHIFT 2
> +#define UCLAMP_PERCENT_SCALE (100 * POW10(UCLAMP_PERCENT_SHIFT))
> + s64 percent;
> + u64 util;
> + int ret;
> +};
> +
> +static inline struct uclamp_request
> +capacity_from_percent(char *buf)
> +{
> + struct uclamp_request req = {
> + .percent = UCLAMP_PERCENT_SCALE,
> + .util = SCHED_CAPACITY_SCALE,
> + .ret = 0,
> + };
> +
> + buf = strim(buf);
> + if (strncmp("max", buf, 4)) {
That is either a bug, and you meant to write: strncmp(buf, "max", 3), or
it is not, and then you could've written: strcmp(buf, "max")
But as written it doesn't make sense.
> + req.ret = cgroup_parse_float(buf, UCLAMP_PERCENT_SHIFT,
> + &req.percent);
> + if (req.ret)
> + return req;
> + if (req.percent > UCLAMP_PERCENT_SCALE) {
> + req.ret = -ERANGE;
> + return req;
> + }
> +
> + req.util = req.percent << SCHED_CAPACITY_SHIFT;
> + req.util = DIV_ROUND_CLOSEST_ULL(req.util, UCLAMP_PERCENT_SCALE);
> + }
> +
> + return req;
> +}
next prev parent reply other threads:[~2019-08-30 9:45 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-22 13:28 [PATCH v14 0/6] Add utilization clamping support (CGroups API) Patrick Bellasi
2019-08-22 13:28 ` [PATCH v14 1/6] sched/core: uclamp: Extend CPU's cgroup controller Patrick Bellasi
2019-08-30 9:45 ` Peter Zijlstra [this message]
2019-09-02 6:38 ` Patrick Bellasi
2019-09-02 7:47 ` Peter Zijlstra
2019-09-02 23:02 ` Suren Baghdasaryan
2019-09-03 8:52 ` Michal Koutný
2019-09-03 14:21 ` Joel Fernandes
2019-08-22 13:28 ` [PATCH v14 2/6] sched/core: uclamp: Propagate parent clamps Patrick Bellasi
2019-08-22 13:28 ` [PATCH v14 3/6] sched/core: uclamp: Propagate system defaults to root group Patrick Bellasi
2019-08-22 13:28 ` [PATCH v14 4/6] sched/core: uclamp: Use TG's clamps to restrict TASK's clamps Patrick Bellasi
2019-08-22 13:28 ` [PATCH v14 5/6] sched/core: uclamp: Update CPU's refcount on TG's clamp changes Patrick Bellasi
2019-08-30 9:48 ` Peter Zijlstra
2019-09-02 6:44 ` Patrick Bellasi
2019-09-02 7:38 ` Peter Zijlstra
2019-08-22 13:28 ` [PATCH v14 6/6] sched/core: uclamp: always use enum uclamp_id for clamp_id values Patrick Bellasi
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