Parallel compression not using all available CPU

[Justin Sherrill]

On the two DragonFly systems, was it Hammer or UFS?  I would be
surprised if that made a difference, but it might?

On Sat, Dec 10, 2016 at 6:19 AM, PeerCorps Trust Fund
<ipc at peercorpstrust.org> wrote:
> Hi,
>
> I've observed that parallel compression tools such as pixz and lbzip2 do not
> make use of all of the available CPU under Dragonfly. On other OSes, it
> does.
>
> When testing on a 50 gb file, using top I've observed that CPU idle
> percentages consistently hover around the 90% range for pixz and ~70% for
> lbzip2. These values under FreeBSD and Linux are typically ~0.0% idle until
> compression is complete. Correspondingly, compression takes significantly
> longer under Dragonfly, so the CPU is really being under utilized in this
> case as opposed to erroneous reporting by top.
>
> This was tested on two systems, one 16c/32t and a 2c/2t system on a recent
> master DragonFly v4.7.0.973.g8d7da-DEVELOPMENT #2: Wed Dec  7 11:44:04 EET
> 2016.
>
> Has anyone else possibly observed this?
>
> --
> Mike
>