Re: Performance of Hurd in a VM

[Malina Sulca <malinasulca@gmail.com>]

On Sat, Apr 7, 2012 at 1:08 AM, Samuel Thibault <sthibault@debian.org> wrote:
>
> Malina Sulca, le Fri 06 Apr 2012 12:16:06 +0800, a écrit :
> > I decided recently to try Hurd, and I thought it best to document it in a blog
> > that you can find here:
> > http://hurdbeginner.blogspot.com/
> >
> > So I installed it in a VM but the I/O is very slow. This is also the case for
> > the pre-installed image that can be downloaded from here:
> > http://people.debian.org/~sthibault/hurd-i386/debian-hurd.img.tar.gz
>
> Which version of kvm and linux are you running exactly? We don't have
> such issues.

My host is a Gentoo with a 3.2.14 vanilla kernel, and I'm using the
qemu-kvm package, which is the qemu found on http://www.linux-kvm.org/
. I run a few VMs on it, so yes KVM is enabled in my kernel and being
used. Just to make sure, I started qemu with the -no-kvm option (since
it's actually enabled by default) and it took GRUB about 1m30s to
start. So the problem is really specific to the disk I/O.

> > How can I improve the overall performance level of the system to make it
> > usable?
>
> As Svante mentioned, enabling the writeback option should help.

Indeed, I used these options and now the system is really usable,
thank you Svante. I'd like to point out that this problem occurs only
with Hurd, whenever the next version is available I'll try again with
the default cache.

> > As a bonus, is it possible to increase the default size of the
> > console? 80x25 feels a bit cramped.
>
> Loading a 8x8 font should work to get 50 lines. You just need to convert
> one to the bdf format and feed the console with it (-f option of the vga
> module).  But as Svante said, it's probably simpler to connect through
> telnet or ssh.

Ouch! I was looking for something a bit more user-friendly here :)
I'll use ssh then, I set up some custom system with a bridge on the
host for the network connections, so I don't have to bother
redirecting ports, hurd gets its own private address :)

> Samuel

Thank you both again for your help!