SMP even/odd cores latency

SMP even/odd cores latency

[DIXLOR]

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# ./cyclictest -sm -n -p99 --policy=fifo -S -D60
# /dev/cpu_dma_latency set to 0us
policy: fifo: loadavg: 2.89 1.37 0.64 1/506 15232

T: 0 (15179) P:99 I:1000 C:  59999 Min:     14 Act:   56 Avg:   51 Max:      99
T: 1 (15180) P:99 I:1500 C:  39999 Min:      3 Act:   13 Avg:   29 Max:     100
T: 2 (15181) P:99 I:2000 C:  29999 Min:     12 Act:   50 Avg:   48 Max:     101
T: 3 (15182) P:99 I:2500 C:  23999 Min:      4 Act:   13 Avg:   29 Max:     101
T: 4 (15183) P:99 I:3000 C:  19999 Min:     16 Act:   60 Avg:   51 Max:     104
T: 5 (15184) P:99 I:3500 C:  17142 Min:      4 Act:   60 Avg:   30 Max:     102
T: 6 (15185) P:99 I:4000 C:  14999 Min:     14 Act:   29 Avg:   51 Max:     106
T: 7 (15186) P:99 I:4500 C:  13333 Min:      4 Act:   11 Avg:   32 Max:     106
T: 8 (15187) P:99 I:5000 C:  11999 Min:     17 Act:   42 Avg:   47 Max:      90
T: 9 (15188) P:99 I:5500 C:  10908 Min:      5 Act:   40 Avg:   29 Max:      89
T:10 (15189) P:99 I:6000 C:   9999 Min:     18 Act:   43 Avg:   49 Max:      99
T:11 (15190) P:99 I:6500 C:   9230 Min:      5 Act:   28 Avg:   29 Max:      99
T:12 (15191) P:99 I:7000 C:   8571 Min:     14 Act:   56 Avg:   47 Max:      98
T:13 (15192) P:99 I:7500 C:   7999 Min:      5 Act:   11 Avg:   31 Max:      97
T:14 (15193) P:99 I:8000 C:   7499 Min:     16 Act:   64 Avg:   49 Max:     100
T:15 (15194) P:99 I:8500 C:   7058 Min:      5 Act:   42 Avg:   30 Max:      96



Minimum latency on even cores is approximately equal to 15, on the odd - 5 
Аverage latency on the even - 50, on the odd cores - 30 :)

- Linux 4.4.1-rt4+ x86_64
- gcc version 4.9.2 (Debian 4.9.2-10)
- 2 x AMD Opteron(tm) Processor 4386
- Mb: TYAN S8225



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Re: SMP even/odd cores latency

[Staffan Tjernstrom]

On ons, 2016-02-03 at 22:06 +0300, DIXLOR wrote:
> > Minimum latency on even cores is approximately equal to 15, on the
> odd - 5 
> Аverage latency on the even - 50, on the odd cores - 30 :)
> > - Linux 4.4.1-rt4+ x86_64
> - gcc version 4.9.2 (Debian 4.9.2-10)
> - 2 x AMD Opteron(tm) Processor 4386
> - Mb: TYAN S8225
> You could confirm by checking /proc/cpuinfo, but it looks like the AMD
cpu enumeration matches that of the last few Intel iterations, where
the even cores are one NUMA node, and the odd the other.