`On Tue, Jul 24, 2018 at 9:43 AM, Patrick Bellasi<patrick.bellasi@arm.com> wrote:> On 21-Jul 21:04, Suren Baghdasaryan wrote:>> On Mon, Jul 16, 2018 at 1:29 AM, Patrick Bellasi>> <patrick.bellasi@arm.com> wrote:>> [...]>>> > +static inline unsigned int scale_from_percent(unsigned int pct)>> > +{>> > +       WARN_ON(pct > 100);>> > +>> > +       return ((SCHED_FIXEDPOINT_SCALE * pct) / 100);>> > +}>> > +>> > +static inline unsigned int scale_to_percent(unsigned int value)>> > +{>> > +       unsigned int rounding = 0;>> > +>> > +       WARN_ON(value > SCHED_FIXEDPOINT_SCALE);>> > +>> > +       /* Compensate rounding errors for: 0, 256, 512, 768, 1024 */>> > +       if (likely((value & 0xFF) && ~(value & 0x700)))>> > +               rounding = 1;>>>> Hmm. I don't think ~(value & 0x700) will ever yield FALSE... What am I missing?>> So, 0x700 is the topmost 3 bits sets (111 0000 0000) which different> configuration corresponds to:>>  001 0000 0000 =>  256>  010 0000 0000 =>  512>  011 0000 0000 =>  768>  100 0000 0000 => 1024>> Thus, if 0x700 matches then we have one of these values in input and> for these cases we have to add a unit to the percentage value.>> For the case (value == 0) we translate it into 0% thanks to the check> on (value & 0xFF) to ensure rounding = 0.>I think just (value & 0xFF) is enough to get you the right behavior.~(value & 0x700) is not needed, it's effectively a NoOp which alwaysyields TRUE. For any *value* (value & 0x700) == 0x...00 and ~(value &0x700) == 0x...FF == TRUE.> Here is a small python snippet I've used to check the conversion of> all the possible percentage values:>> ---8<---> values = range(0, 101)> for pct in xrange(0, 101):>         util = int((1024 * pct) / 100)>         rounding = 1>         if not ((util & 0xFF) and ~(util & 0x700)):>             print "Fixing util_to_perc({:3d} => {:4d})".format(pct, util)>             rounding = 0>         pct2 = (rounding + ((100 * util) / 1024))>         if pct2 in values:>                 values.remove(pct2)>         if pct != pct2:>             print "Convertion failed for: {:3d} => {:4d} => {:3d}".format(pct, util, pct2)> if values:>     print "ERROR: not all percentage values converted"> ---8<--->> --> #include <best/regards.h>>> Patrick Bellasi`