high load in KVM when network is used (stable/10)

[Armin Pirkovitsch]

Hi,

has anyone ever experienced a problem with FreeBSD 10 (release as well
as stable) in KVMs? (in relation to network activity)

Currently the load of my server goes up when I just fetch a file.

systat -vmstat
>     3 users    Load  0.57  0.28  0.28                  May  5 21:04
> 
> Mem:KB    REAL            VIRTUAL                       VN PAGER   SWAP PAGER
>         Tot   Share      Tot    Share    Free           in   out     in   out
> Act  714476   27764  2951164    33696  14130k  count
> All 2002012   83188  3211064   209272          pages
> Proc:                                                            Interrupts
>   r   p   d   s   w   Csw  Trp  Sys  Int  Sof  Flt        ioflt  4575 total
>   2         102       11k   17  25k 4046   38             cow         atkbd0 1
>                                                           zfod        uhci0 11
> 28.6%Sys  14.3%Intr  1.4%User  0.0%Nice 55.7%Idle         ozfod       ata1 15
> |    |    |    |    |    |    |    |    |    |           %ozfod   121 cpu0:timer
> ==============+++++++>                                    daefr  3255 virtio_pci
>                                            dtbuf          prcfr       virtio_pci
> Namei     Name-cache   Dir-cache    350329 desvn          totfr   790 virtio_pci
>    Calls    hits   %    hits   %      6556 numvn          react   116 cpu3:timer
>        6       6 100                  4181 frevn          pdwak   185 cpu2:timer
>                                                       210 pdpgs   108 cpu1:timer
> Disks vtbd0   cd0 pass0                                   intrn      
> KB/t    120  0.00  0.00                           1382576 wire       
> tps     788     0     0                            504540 act
> MB/s  92.55  0.00  0.00                            291232 inact
> %busy    49     0     0                                   cache
>                                                  14130808 free
>                                                           buf

it's even worse when I access apache on that server:
>     3 users    Load  4.63  1.33  0.66                  May  5 21:06
> 
> Mem:KB    REAL            VIRTUAL                       VN PAGER   SWAP PAGER
>         Tot   Share      Tot    Share    Free           in   out     in   out
> Act  727760   27764  2938852    33696  14116k  count
> All 2015420   83188  3198752   209272          pages
> Proc:                                                            Interrupts
>   r   p   d   s   w   Csw  Trp  Sys  Int  Sof  Flt        ioflt     8 total
>             103        14    4   49    2    1             cow         atkbd0 1
>                                                           zfod        uhci0 11
> 68.8%Sys  31.2%Intr  0.0%User  0.0%Nice  0.0%Idle         ozfod       ata1 15
> |    |    |    |    |    |    |    |    |    |           %ozfod     1 cpu0:timer
> ==================================++++++++++++++++        daefr     4 virtio_pci
>                                            dtbuf          prcfr       virtio_pci
> Namei     Name-cache   Dir-cache    350329 desvn          totfr     1 virtio_pci
>    Calls    hits   %    hits   %      6557 numvn          react       cpu3:timer
>        6       6 100                  4136 frevn          pdwak     1 cpu2:timer
>                                                       136 pdpgs     1 cpu1:timer
> Disks vtbd0   cd0 pass0                                   intrn      
> KB/t    128  0.00  0.00                           1382808 wire       
> tps       1     0     0                            506072 act
> MB/s   0.11  0.00  0.00                            303460 inact
> %busy    33     0     0                                   cache
>                                                  14116816 free
>                                                           buf

and you couldn't say that it just hasn't got enough power...
...
> CPU: Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz (2000.01-MHz K8-class CPU)
>   Origin = "GenuineIntel"  Id = 0x206d7  Family = 0x6  Model = 0x2d  Stepping = 7
>   Features=0xf83fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FXSR,SSE,SSE2,SS>
>   Features2=0x9eb82203<SSE3,PCLMULQDQ,SSSE3,CX16,SSE4.1,SSE4.2,x2APIC,POPCNT,AESNI,XSAVE,OSXSAVE,AVX,HV>
>   AMD Features=0x2c100800<SYSCALL,NX,Page1GB,RDTSCP,LM>
>   AMD Features2=0x1<LAHF>
> real memory  = 17179869184 (16384 MB)
> avail memory = 16597995520 (15829 MB)
> Event timer "LAPIC" quality 400
> ACPI APIC Table: <BOCHS  BXPCAPIC>
> FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
> FreeBSD/SMP: 4 package(s) x 1 core(s)
...

Has someone any suggestions what I could do to improve the performance
(and lower the load)?

Cheers
Armin