sshd responsiveness

Carsten Mattner carstenmattner at
Sun Feb 10 10:58:43 PST 2013

On Sun, Feb 10, 2013 at 7:53 PM, Justin Sherrill
<justin at> wrote:
> Well, it's two different file systems, two different operating systems, and
> (I assume) two different machines with different disks and different network
> links.  Maybe even two different encryption setups?  I don't know if the
> FreeBSD machine is using ZFS or UFS - if it's UFS, it's not recording
> history so there's less overall work.  That can make a difference too.
> Unfortunately this all adds up to a shoulder shrug, in terms of an answer.
> There's been a lot of discussion about the disk scheduler and how to
> position reading vs. writing for Hammer over the past year or two.  If you
> really want to dive into it, there's the 'dsched' man page, and the other
> pages it links to from there.  Also, there's scheduler-related links on the
> Digest:

Thanks Justin.

It's actually the same machine and I'm pretty much curious
about interactive sessions and the process scheduler and
real world experience users have or can relate to.

> On Sun, Feb 10, 2013 at 5:17 AM, Carsten Mattner <carstenmattner at>
> wrote:
>> When I compared FreeBSD 9.1 geli based full disk encrypted system
>> with a dfly (HAMMER) 3.2.2 full disk encrypted system I noticed that
>> using an ssh session is considerably less responsive on dfly if I
>> rsync data from another machine to the dfly machine in parallel.
>> On FreeBSD the ssh session doesn't get unresponsive. This is
>> subjective and not scientifically measured and I'm just curious
>> to hear your thoughts. Is it just probably caused by default settings?

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