On 11/06/2014 04:41 μμ, Doug Smythies wrote: > > On 2014.06.11 05:34 Stratos Karafotis wrote: > >> Local variable core_pct holds fixed point values. >> When we round it we add "1" to core_pct. This has almost >> no effect. >> >> So, add int_toftp(1) to core_pct when rounding. >> >> For example, in a given sample point (values taken from >> tracepoint) with: >> aperf = 5024 >> mperf = 10619 >> >> the core_pct is (before rounding): >> core_pct = 12111 >> fp_toint(core_pct) = 47 >> >> After rounding: >> core_pct = 12112 >> fp_toint(core_pct) = 47 >> >> After rounding with int_toftp(1): >> core_pct = 12367 >> fp_toint(core_pct) = 48 >> >> Signed-off-by: Stratos Karafotis <strat...@semaphore.gr> >> --- >> >> Hi Rafael, >> >> I'm sorry for submitting again in merge window, but >> I thought that maybe we need this fix for 3.16. >> >> >> drivers/cpufreq/intel_pstate.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c >> index 4e7f492..dd80aa2 100644 >> --- a/drivers/cpufreq/intel_pstate.c >> +++ b/drivers/cpufreq/intel_pstate.c >> @@ -564,7 +564,7 @@ static inline void intel_pstate_calc_busy(struct cpudata >> *cpu) >> core_pct = div_u64_rem(core_pct, int_tofp(sample->mperf), &rem); >> >> 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. >
Are you sure? This rounding was very recently added. As far as I can understand, I don't see the meaning of this rounding, as is. Even if FRAC_BITS was 6, I think it would have almost no improvement in calculations. Stratos -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
