Re: [PATCH v14 1/6] sched/core: uclamp: Extend CPU's cgroup controller
flat view
From: Peter Zijlstra <peterz@infradead.org>
Date: 2019-08-30 09:45:31
Also in:
cgroups, linux-pm, lkml
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!
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+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.
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+ 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; +}