Core 0 constantly bogged down by interrupts

[Mike Zhang]

Hi everyone, newbie here...

I'm in the process of migrating to DragonFly for my main desktop as I
figured it would make more efficient use of SMP than my former OS of choice.
Ironically the problem I'm running into is core 0 seems to be constantly
maxing out with about 60-70% going to Interrupts and the rest to System.
This happens both under heavy loads:

> load averages:  4.03,  4.38,  4.49;               up 14+03:18:26       13:34:08
> 90 processes: 6 running, 90 active
> CPU states:  0.0% user,  2.8% nice, 39.8% system, 57.4% interrupt,  0.0% idle
> CPU states:  0.0% user, 35.7% nice,  8.4% system,  0.0% interrupt, 55.9% idle
> CPU states:  0.0% user, 82.5% nice,  5.6% system,  0.0% interrupt, 11.9% idle
> CPU states:  0.0% user, 14.7% nice,  2.8% system,  0.0% interrupt, 82.5% idle
> Memory: 2319M Active, 3665M Inact, 5464M Wired, 493M Cache, 1592M Buf, 3679M Free
> Swap: 32G Total, 81M Used, 32G Free

And while mostly (or entirely) idle:

> load averages:  0.44,  0.37,  0.30;               up 1+03:14:08        15:36:26
> 56 processes: 1 running, 56 active
> CPU states:  0.0% user,  0.7% nice, 24.6% system, 71.2% interrupt,  3.5% idle
> CPU states:  0.0% user,  0.0% nice,  0.7% system,  0.0% interrupt, 99.3% idle
> CPU states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
> CPU states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
> Memory: 647M Active, 6448M Inact, 3769M Wired, 766M Cache, 1523M Buf, 3991M Free
> Swap: 32G Total, 63M Used, 32G Free

It even happens in single user mode:

> load averages:  0.11,  0.05,  0.02;               up 0+00:01:46        16:01:04
> 2 processes: 1 running, 2 active
> CPU states:  0.0% user,  0.0% nice, 21.0% system, 76.2% interrupt,  2.8% idle
> CPU states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
> CPU states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
> CPU states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
> Memory: 1188K Active, 128K Inact, 1112M Wired, 4680K Cache, 30M Buf, 14G Free
> Swap: 
> 
>    PID USERNAME   NICE  SIZE    RES    STATE   C   TIME   CTIME    CPU COMMAND
>     42 root         0  4392K  2220K     CPU2   2   0:00    0:00  0.00% top
>     20 root         0  4320K  1800K     wait   1   0:00    0:00  0.00% sh

I am using a GENERIC kernel from master on an i5-6600 @ 3.30GHz, with i915
for graphics and my NIC set to poll.  My FS is HAMMER on a dm-crypt device
and this is an EFI install on a single hard drive.

I'm not sure what it is that I'm doing wrong here but any pointers would be
much appreciated...

Mike