[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v3 05/14 RESEND] xenpm: Change get-cpufreq-para output for internal
On 04.05.2023 19:00, Jason Andryuk wrote: > On Thu, May 4, 2023 at 10:35 AM Jan Beulich <jbeulich@xxxxxxxx> wrote: >> >> On 01.05.2023 21:30, Jason Andryuk wrote: >>> When using HWP, some of the returned data is not applicable. In that >>> case, we should just omit it to avoid confusing the user. So switch to >>> printing the base and turbo frequencies since those are relevant to HWP. >>> Similarly, stop printing the CPU frequencies since those do not apply. >> >> It vaguely feels like I have asked this before: Can you point me at a >> place in the SDM where it is said that CPUID 0x16's "Maximum Frequency" >> is the turbo frequency? Without such a reference I feel a little uneasy >> with ... > > I don't have a reference, but I found it empirically to match the > "turbo" frequency. > > For an Intel® Core™ i7-10810U, > https://ark.intel.com/content/www/us/en/ark/products/201888/intel-core-i710810u-processor-12m-cache-up-to-4-90-ghz.html > > Max Turbo Frequency 4.90 GHz > > # xenpm get-cpufreq-para > cpu id : 0 > affected_cpus : 0 > cpuinfo frequency : base [1600000] turbo [4900000] > > Turbo has to be enabled to reach (close to) that frequency. > > From my cover letter: > This is for a 10th gen 6-core 1600 MHz base 4900 MHZ max cpu. In the > default balance mode, Turbo Boost doesn't exceed 4GHz. Tweaking the > energy_perf preference with `xenpm set-cpufreq-hwp balance ene:64`, > I've seen the CPU hit 4.7GHz before throttling down and bouncing around > between 4.3 and 4.5 GHz. Curiously the other cores read ~4GHz when > turbo boost takes affect. This was done after pinning all dom0 cores, > and using taskset to pin to vCPU/pCPU 11 and running a bash tightloop. Right, but what matters for the longer term future is what gets committed (and the cover letter won't be). IOW ... >>> @@ -720,10 +721,15 @@ static void print_cpufreq_para(int cpuid, struct >>> xc_get_cpufreq_para *p_cpufreq) >>> printf(" %d", p_cpufreq->affected_cpus[i]); >>> printf("\n"); >>> >>> - printf("cpuinfo frequency : max [%u] min [%u] cur [%u]\n", >>> - p_cpufreq->cpuinfo_max_freq, >>> - p_cpufreq->cpuinfo_min_freq, >>> - p_cpufreq->cpuinfo_cur_freq); >>> + if ( internal ) >>> + printf("cpuinfo frequency : base [%u] turbo [%u]\n", >>> + p_cpufreq->cpuinfo_min_freq, >>> + p_cpufreq->cpuinfo_max_freq); >> >> ... calling it "turbo" (and not "max") here. > > I'm fine with "max". I think I went with turbo since it's a value you > cannot sustain but can only hit in short bursts. ... I don't mind you sticking to "turbo" as long as the description makes clear why that was chosen despite the SDM not naming it this way. Jan
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