: root 3 0.0 0.0 0 0 ? S 18:51 0:00 [watchdog/0]
That's the softlockup detector. Confusingly named to look like a, err,
watchdog. Could probably use keventd.
: root 5 0.0 0.0 0 0 ? S 18:51 0:00 [khelper]
That's there to parent the kthread_create()d threads. Could presumably use
khelper.
: root 152 0.0 0.0 0 0 ? S 18:51 0:00 [ata/0]
Does it need to be per-cpu?
: root 153 0.0 0.0 0 0 ? S 18:51 0:00 [ata_aux]
That's a single-threaded workqueue handler. Perhaps could use keventd.
: root 299 0.0 0.0 0 0 ? S 18:51 0:00 [scsi_eh_0]
: root 300 0.0 0.0 0 0 ? S 18:51 0:00 [scsi_eh_1]
: root 305 0.0 0.0 0 0 ? S 18:51 0:00 [scsi_eh_2]
: root 306 0.0 0.0 0 0 ? S 18:51 0:00 [scsi_eh_3]
This machine has one CPU, one sata disk and one DVD drive. The above is
hard to explain.
: root 319 0.0 0.0 0 0 ? S 18:51 0:00 [pccardd]
hm.
: root 331 0.0 0.0 0 0 ? S 18:51 0:00 [kpsmoused]
hm.
: root 337 0.0 0.0 0 0 ? S 18:51 0:00 [kedac]
hm. I didn't know that the Vaio had EDAC.
: root 1173 0.0 0.0 0 0 ? S 18:51 0:00 [khpsbpkt]
I can't even pronounce that.
: root 1354 0.0 0.0 0 0 ? S 18:51 0:00 [knodemgrd_0]
OK, I do have 1394 hardware, but it hasn't been used.
: root 1636 0.0 0.0 0 0 ? S 18:52 0:00 [kondemand/0]
I blame davej.
> otoh, a lot of these inefficeincies are probably down in scruffy drivers
> rather than in core or top-level code.
You say scruffy, but most of the proliferation of kthreads comes
from code written in the last few years. Compare the explosion of kthreads
we see coming from 2.4 to 2.6. It's disturbing, and I don't see it
slowing down at all.
On the 2-way box I grabbed the above ps output from, I end up with 69 kthreads.
It doesn't surprise me at all that bigger iron is starting to see issues.
Sure.
I don't think it's completely silly to object to all this. Sure, a kernel
thread is worth 4k in the best case, but I bet they have associated unused
resources and as we've seen, they can cause overhead.