On 2014.06.11 06:42 Doug Smythies wrote:
On 2014.06.11 05:34 Stratos Karafotis wrote:
>> if ((rem << 1) >= int_tofp(sample->mperf))
>> - core_pct += 1;
>> + core_pct += int_tofp(1);
>>
>> sample->freq = fp_toint(
>> mul_fp(int_tofp(cpu->pstate.max_pstate * 1000), core_pct));
>> --
>> 1.9.3
> No.
> The intent was only ever to round properly the pseudo floating
> point result of the divide.
> It was much more important (ugh, well 4 times more) when
> FRACBITS was still 6, which also got changed to 8 in a recent
> patch.
I forgot to mention there are other related roundings that are being considered.
I do not recall clearly, but I think Dirk and I agreed to hold off until
the recent panics had settled.
The analysis as to the importance needs to be re-done, as it was all done when
FRACBITS was 6. Things were very "chunky" when
FRACBITS was 6.
These are what I was considering putting forward:
static inline int32_t fp_toint(int32_t x)
{
if (x >= 0)
x += (1 << (FRAC_BITS -1));
else
x -= (1 << (FRAC_BITS -1));
return (x >> FRAC_BITS);
}
static inline int32_t mul_fp(int32_t x, int32_t y)
{
int64_t temp;
temp = (int64_t)x * (int64_t)y;
if (temp >= 0)
temp += (1 << (FRAC_BITS -1));
else
temp -= (1 << (FRAC_BITS -1));
return (temp >> FRAC_BITS);
}
static inline int32_t div_fp(int32_t x, int32_t y)
{
/* currently, there are only positive numbers to worry about here */
int32_t rem;
x = div_s64_rem((int64_t)x << FRAC_BITS, (int64_t)y, &rem);
if((rem << 1) >= y) x++;
return(x);
}
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