100% intr CPU state in OpenBSD 6.4 VM

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100% intr CPU state in OpenBSD 6.4 VM

mabi
Hi,

I am testing VMM/VMD on an OpenBSD 6.4 host with an OpenBSD 6.4 as guest OS and noticed that on a fresh installation the CPU seems to be all the time 100% busy dealing with interrupts. Here is the relevant line from "top":

CPU states:  0.0% user,  0.0% nice,  0.0% sys,  0.0% spin,  100% intr,  0.0% idle

And the output of "vmstat" looks like this:
vmstat 1
 procs    memory       page                    disk traps          cpu
 r   s   avm     fre  flt  re  pi  po  fr  sr sd0  int   sys   cs us sy id
 1  32   15M    668M    4   0   0   0   0   0   0  102    12   14  0 99  1
 0  33   15M    668M   12   0   0   0   0   0   0  210    41   41  0 98  2
 0  33   15M    668M    7   0   0   0   0   0   0  207    36   33  0 99  1
 0  33   15M    668M    7   0   0   0   0   0   0  210    37   36  0 98  2
 0  33   15M    668M    7   0   0   0   0   0   0  209    37   36  0 100  0

The "Interrupts" column in the output of "systat" looks like this:

Interrupts
276 total
    virtio0
    virtio1
15  virtio2
     com0
133 clock
128 rtc

This VM has nothing running yet, the only thing I did is to disable sndiod and change this kernel parameter so that the time in the VM is more accurate:

kern.timecounter.hardware=tsc

So my question here would be if this 100% interrupt usage is normal under an OpenBSD VM? or is there something I might be doing wrong?

Below I pasted the "dmesg" output of my VM. Let me know if more details are required.

Regards,
Mabi


OpenBSD 6.4 (GENERIC) #3: Thu Dec 20 18:31:57 CET 2018
    [hidden email]:/usr/src/sys/arch/amd64/compile/GENERIC
real mem = 1056956416 (1007MB)
avail mem = 1015816192 (968MB)
mpath0 at root
scsibus0 at mpath0: 256 targets
mainbus0 at root
bios0 at mainbus0: SMBIOS rev. 2.4 @ 0xf1950 (10 entries)
bios0: vendor SeaBIOS version "1.11.0p0-OpenBSD-vmm" date 01/01/2011
bios0: OpenBSD VMM
acpi at bios0 not configured
cpu0 at mainbus0: (uniprocessor)
cpu0: Intel(R) Xeon(R) CPU E5620 @ 2.40GHz, 2396.03 MHz, 06-2c-02
cpu0: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,MMX,FXSR,SSE,SSE2,SSE3,PCLMUL,SSSE3,CX16,SSE4.1,SSE4.2,POPCNT,AES,HV,NXE,PAGE1GB,LONG,LAHF,ITSC,MELTDOWN
cpu0: 256KB 64b/line 8-way L2 cache
cpu0: smt 0, core 0, package 0
pvbus0 at mainbus0: OpenBSD
pci0 at mainbus0 bus 0
pchb0 at pci0 dev 0 function 0 "OpenBSD VMM Host" rev 0x00
virtio0 at pci0 dev 1 function 0 "Qumranet Virtio RNG" rev 0x00
viornd0 at virtio0
virtio0: irq 3
virtio1 at pci0 dev 2 function 0 "Qumranet Virtio Storage" rev 0x00
vioblk0 at virtio1
scsibus1 at vioblk0: 2 targets
sd0 at scsibus1 targ 0 lun 0: <VirtIO, Block Device, > SCSI3 0/direct fixed
sd0: 51200MB, 512 bytes/sector, 104857600 sectors
virtio1: irq 5
virtio2 at pci0 dev 3 function 0 "Qumranet Virtio Network" rev 0x00
vio0 at virtio2: address fe:e1:bb:ff:ff:ff
virtio2: irq 6
virtio3 at pci0 dev 4 function 0 "OpenBSD VMM Control" rev 0x00
vmmci0 at virtio3
virtio3: irq 7
isa0 at mainbus0
isadma0 at isa0
com0 at isa0 port 0x3f8/8 irq 4: ns16450, no fifo
com0: console
vscsi0 at root
scsibus2 at vscsi0: 256 targets
softraid0 at root
scsibus3 at softraid0: 256 targets
root on sd0a (2c1a48e720407786.a) swap on sd0b dump on sd0b


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Re: 100% intr CPU state in OpenBSD 6.4 VM

Mike Larkin
On Thu, Jan 24, 2019 at 01:17:01PM +0000, mabi wrote:

> Hi,
>
> I am testing VMM/VMD on an OpenBSD 6.4 host with an OpenBSD 6.4 as guest OS and noticed that on a fresh installation the CPU seems to be all the time 100% busy dealing with interrupts. Here is the relevant line from "top":
>
> CPU states:  0.0% user,  0.0% nice,  0.0% sys,  0.0% spin,  100% intr,  0.0% idle
>
> And the output of "vmstat" looks like this:
> vmstat 1
>  procs    memory       page                    disk traps          cpu
>  r   s   avm     fre  flt  re  pi  po  fr  sr sd0  int   sys   cs us sy id
>  1  32   15M    668M    4   0   0   0   0   0   0  102    12   14  0 99  1
>  0  33   15M    668M   12   0   0   0   0   0   0  210    41   41  0 98  2
>  0  33   15M    668M    7   0   0   0   0   0   0  207    36   33  0 99  1
>  0  33   15M    668M    7   0   0   0   0   0   0  210    37   36  0 98  2
>  0  33   15M    668M    7   0   0   0   0   0   0  209    37   36  0 100  0
>
> The "Interrupts" column in the output of "systat" looks like this:
>
> Interrupts
> 276 total
>     virtio0
>     virtio1
> 15  virtio2
>      com0
> 133 clock
> 128 rtc
>
> This VM has nothing running yet, the only thing I did is to disable sndiod and change this kernel parameter so that the time in the VM is more accurate:
>
> kern.timecounter.hardware=tsc
>
> So my question here would be if this 100% interrupt usage is normal under an OpenBSD VM? or is there something I might be doing wrong?
>
> Below I pasted the "dmesg" output of my VM. Let me know if more details are required.
>
> Regards,
> Mabi
>
>
> OpenBSD 6.4 (GENERIC) #3: Thu Dec 20 18:31:57 CET 2018
>     [hidden email]:/usr/src/sys/arch/amd64/compile/GENERIC
> real mem = 1056956416 (1007MB)
> avail mem = 1015816192 (968MB)
> mpath0 at root
> scsibus0 at mpath0: 256 targets
> mainbus0 at root
> bios0 at mainbus0: SMBIOS rev. 2.4 @ 0xf1950 (10 entries)
> bios0: vendor SeaBIOS version "1.11.0p0-OpenBSD-vmm" date 01/01/2011
> bios0: OpenBSD VMM
> acpi at bios0 not configured
> cpu0 at mainbus0: (uniprocessor)
> cpu0: Intel(R) Xeon(R) CPU E5620 @ 2.40GHz, 2396.03 MHz, 06-2c-02
> cpu0: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,MMX,FXSR,SSE,SSE2,SSE3,PCLMUL,SSSE3,CX16,SSE4.1,SSE4.2,POPCNT,AES,HV,NXE,PAGE1GB,LONG,LAHF,ITSC,MELTDOWN
> cpu0: 256KB 64b/line 8-way L2 cache
> cpu0: smt 0, core 0, package 0
> pvbus0 at mainbus0: OpenBSD
> pci0 at mainbus0 bus 0
> pchb0 at pci0 dev 0 function 0 "OpenBSD VMM Host" rev 0x00
> virtio0 at pci0 dev 1 function 0 "Qumranet Virtio RNG" rev 0x00
> viornd0 at virtio0
> virtio0: irq 3
> virtio1 at pci0 dev 2 function 0 "Qumranet Virtio Storage" rev 0x00
> vioblk0 at virtio1
> scsibus1 at vioblk0: 2 targets
> sd0 at scsibus1 targ 0 lun 0: <VirtIO, Block Device, > SCSI3 0/direct fixed
> sd0: 51200MB, 512 bytes/sector, 104857600 sectors
> virtio1: irq 5
> virtio2 at pci0 dev 3 function 0 "Qumranet Virtio Network" rev 0x00
> vio0 at virtio2: address fe:e1:bb:ff:ff:ff
> virtio2: irq 6
> virtio3 at pci0 dev 4 function 0 "OpenBSD VMM Control" rev 0x00
> vmmci0 at virtio3
> virtio3: irq 7
> isa0 at mainbus0
> isadma0 at isa0
> com0 at isa0 port 0x3f8/8 irq 4: ns16450, no fifo
> com0: console
> vscsi0 at root
> scsibus2 at vscsi0: 256 targets
> softraid0 at root
> scsibus3 at softraid0: 256 targets
> root on sd0a (2c1a48e720407786.a) swap on sd0b dump on sd0b
>
>

I believe this to be an accounting error and has been discussed on the lists
several times.

-ml

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Re: 100% intr CPU state in OpenBSD 6.4 VM

mabi
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Thursday, January 24, 2019 5:35 PM, Mike Larkin <[hidden email]> wrote:

> I believe this to be an accounting error and has been discussed on the lists
> several times.
>

Sorry about that, now that you mention I remember also reading something on the list about that but could not find anything on ddg search.

I have an issue where my VM temporary loses network connection for a few seconds to a few minutes so I was wondering if it might have been related to the high amount of interrupts but in that case it is not. I will look in other directions...