On 05/16/2018 03:34 PM, Wido den Hollander wrote:
> 
> 
> On 05/16/2018 01:22 PM, Blair Bethwaite wrote:
>> On 15 May 2018 at 08:45, Wido den Hollander <w...@42on.com
>> <mailto:w...@42on.com>> wrote:
>>
>>     > We've got some Skylake Ubuntu based hypervisors that we can look at to
>>     > compare tomorrow...
>>     > 
>>
>>     Awesome!
>>
>>
>> Ok, so results still inconclusive I'm afraid...
>>
>> The Ubuntu machines we're looking at (Dell R740s and C6420s running with
>> Performance BIOS power profile, which amongst other things disables
>> cstates and enables turbo) are currently running either a 4.13 or a 4.15
>> HWE kernel - we needed 4.13 to support PERC10 and even get them booting
>> from local storage, then 4.15 to get around a prlimit bug that was
>> breaking Nova snapshots, so here we are. Where are you getting 4.16,
>> http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.16/ ?
>>
> 
> Yes, that's where I got 4.16: 4.16.7-041607-generic
> 
> I also tried 4.16.8, but that didn't change anything either.
> 
> Server I am testing with are these:
> https://www.supermicro.nl/products/system/1U/1029/SYS-1029U-TN10RT.cfm
> 
>> So interestingly in our case we seem to have no cpufreq driver loaded.
>> After installing linux-generic-tools (cause cpupower is supposed to
>> supersede cpufrequtils I think?):
>>
>> rr42-03:~$ uname -a
>> Linux rcgpudc1rr42-03 4.15.0-13-generic #14~16.04.1-Ubuntu SMP Sat Mar
>> 17 03:04:59 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
>>
>> rr42-03:~$ cat /proc/cmdline
>> BOOT_IMAGE=/vmlinuz-4.15.0-13-generic root=/dev/mapper/vg00-root ro
>> intel_iommu=on iommu=pt intel_idle.max_cstate=0 processor.max_cstate=1
>>
> 
> I have those settings as well, intel_idle and processor.max_cstate.
> 
> [    1.776036] intel_idle: disabled
> 

Ok, so this caught my attention, why was that module disabled? So I
started to dig deeper and deeper.

It seems that max_cstate=0 for intel_idle actually seems to disable it.

So I'm now using: 'processor.max_cstate=1 intel_idle.max_cstate=1'

I ran my tests again and here is what I get with fio and iodepth=1 with
a randwrite test of 4k. Below is a list of kernels and the usec latency:

- 4.4: 1957
- 4.13: 1259
- 4.16: 918

Again, this is with a Dual Xeon Silver 4110 with NVMe SSDs.

With the performance governor the CPUs now stay pinned on 2.4Ghz:

analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 3.00 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 800 MHz and 3.00 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 2.40 GHz.

Going to test further with Ceph OSD options and such, but this seems
like a lot better result.

> That works, the CPUs stay in C0 or C1 according to i7z, but they are
> clocking down in Mhz, for example:
> 
> processor     : 23
> vendor_id     : GenuineIntel
> cpu family    : 6
> model         : 85
> model name    : Intel(R) Xeon(R) Silver 4110 CPU @ 2.10GHz
> stepping      : 4
> microcode     : 0x2000043
> cpu MHz               : 799.953
> 
> /sys/devices/system/cpu/intel_pstate/min_perf_pct is set to 100, but
> that setting doesn't seem to do anything.
> 
> I'm running out of ideas :-)
> 
> Wido
> 
>> rr42-03:~$ lscpu
>> Architecture:          x86_64
>> CPU op-mode(s):        32-bit, 64-bit
>> Byte Order:            Little Endian
>> CPU(s):                36
>> On-line CPU(s) list:   0-35
>> Thread(s) per core:    1
>> Core(s) per socket:    18
>> Socket(s):             2
>> NUMA node(s):          2
>> Vendor ID:             GenuineIntel
>> CPU family:            6
>> Model:                 85
>> Model name:            Intel(R) Xeon(R) Gold 6150 CPU @ 2.70GHz
>> Stepping:              4
>> CPU MHz:               3400.956
>> BogoMIPS:              5401.45
>> Virtualization:        VT-x
>> L1d cache:             32K
>> L1i cache:             32K
>> L2 cache:              1024K
>> L3 cache:              25344K
>> NUMA node0 CPU(s):     0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34
>> NUMA node1 CPU(s):     1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35
>> Flags:                 fpu vme de pse tsc msr pae mce cx8 apic sep mtrr
>> pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe
>> syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts
>> rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq
>> dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid
>> dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx
>> f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3
>> invpcid_single pti intel_ppin mba tpr_shadow vnmi flexpriority ept vpid
>> fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm mpx
>> rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd
>> avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc
>> cqm_mbm_total cqm_mbm_local ibpb ibrs stibp dtherm ida arat pln pts pku
>> ospke
>>
>> rr42-03:~$ sudo cpupower frequency-info
>> analyzing CPU 0:
>>   no or unknown cpufreq driver is active on this CPU
>>   CPUs which run at the same hardware frequency: Not Available
>>   CPUs which need to have their frequency coordinated by software: Not
>> Available
>>   maximum transition latency:  Cannot determine or is not supported.
>> Not Available
>>   available cpufreq governors: Not Available
>>   Unable to determine current policy
>>   current CPU frequency: Unable to call hardware
>>   current CPU frequency:  Unable to call to kernel
>>   boost state support:
>>     Supported: yes
>>     Active: yes
>>
>>
>> And of course there is nothing under sysfs (/sys/devices/system/cpu*).
>> But /proc/cpuinfo and cpupower-monitor show that we seem to be hitting
>> turbo freqs:
>>
>> rr42-03:~$ sudo cpupower monitor
>>               |Nehalem                    || Mperf
>> PKG |CORE|CPU | C3   | C6   | PC3  | PC6  || C0   | Cx   | Freq
>>    0|   0|   0|  0.00|  0.00|  0.00|  0.00||  0.05| 99.95|  3391
>>    0|   1|   4|  0.00|  0.00|  0.00|  0.00||  0.02| 99.98|  3389
>>    0|   2|   8|  0.00|  0.00|  0.00|  0.00||  0.14| 99.86|  3067
>>    0|   3|   6|  0.00|  0.00|  0.00|  0.00||  0.01| 99.99|  3385
>>    0|   4|   2|  0.00|  0.00|  0.00|  0.00||  0.09| 99.91|  3119
>>    0|   8|  12|  0.00|  0.00|  0.00|  0.00||  0.03| 99.97|  3312
>>    0|   9|  16|  0.00|  0.00|  0.00|  0.00||  0.11| 99.89|  3157
>>    0|  10|  14|  0.00|  0.00|  0.00|  0.00||  0.01| 99.99|  3352
>>    0|  11|  10|  0.00|  0.00|  0.00|  0.00||  0.05| 99.95|  3390
>>    0|  16|  20|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3387
>>    0|  17|  24|  0.00|  0.00|  0.00|  0.00||  0.22| 99.78|  3115
>>    0|  18|  26|  0.00|  0.00|  0.00|  0.00||  0.01| 99.99|  3389
>>    0|  19|  22|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3366
>>    0|  20|  18|  0.00|  0.00|  0.00|  0.00||  0.01| 99.99|  3392
>>    0|  24|  28|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3376
>>    0|  25|  32|  0.00|  0.00|  0.00|  0.00||  0.05| 99.95|  3390
>>    0|  26|  34|  0.00|  0.00|  0.00|  0.00||  0.03| 99.97|  3391
>>    0|  27|  30|  0.00|  0.00|  0.00|  0.00||  0.01| 99.99|  3392
>>    1|   0|   1|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3394
>>    1|   1|   5|  0.00|  0.00|  0.00|  0.00||  0.01| 99.99|  3378
>>    1|   2|   9|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3393
>>    1|   3|   7|  0.00|  0.00|  0.00|  0.00||  0.01| 99.99|  3384
>>    1|   4|   3|  0.00|  0.00|  0.00|  0.00||  0.02| 99.98|  3391
>>    1|   8|  13|  0.00|  0.00|  0.00|  0.00||  0.01| 99.99|  3390
>>    1|   9|  17|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3391
>>    1|  10|  15|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3360
>>    1|  11|  11|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3393
>>    1|  16|  21|  0.00|  0.00|  0.00|  0.00||  0.01| 99.99|  3397
>>    1|  17|  25|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3391
>>    1|  18|  27|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3376
>>    1|  19|  23|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3334
>>    1|  20|  19|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3387
>>    1|  24|  29|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3377
>>    1|  25|  33|  0.00|  0.00|  0.00|  0.00||  0.01| 99.99|  3387
>>    1|  26|  35|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3392
>>    1|  27|  31|  0.00|  0.00|  0.00|  0.00||  0.00|100.00|  3392
>>
>>
>> On a similar node with the 4.13 kernel we get similar reports from
>> cpupower-monitor, but oddly on 4.13 /proc/cpuinfo shows all cores at
>> base 2700.000 (on 4.15 it updates).
>>
>> We can try 4.16 tomorrow. But I wonder why we are already seeing turbo
>> even at idle and you aren't... only thing I can think of is that it must
>> be because our cstates are disabled in BIOS, indeed when looking in
>> dmesg I see:
>>
>> [    1.274325] intel_idle: disabled
>>
>> So it stands to reason that intel_idle.max_cstate=0 is doing nothing for
>> either of us. What do you see from intel_idle on 4.16?
>>
>> -- 
>> Cheers,
>> ~Blairo
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