Re: Serious WAPL performance problems

[Stephan <stephanwib%googlemail.com@localhost>]

Hi Roger

It is funny someone from Citrix is responding to this NetBSD topic - I
maintain a very huge Citrix installation including XenServer, XenApp
and Provisioning Services.

> I've
> added some debugging to xbd_xenbus, to see if we where issuing a lot of
> flushes or requests, and I've found out that most of the time the kernel
> seems to be sending spaced read requests, and when jumping into ddb the
> kernel is almost always in VOP_LOOKUP or ufs_lookup (forget about
> anything above and including the hypervisor_callback call):

If VirtualBox is not lying, the disk is barely accessed all the time.
As for the kernel trace, I often see VOP_LOOKUP but I find it more
often in VOP_CREATE for me - both follow-ups from touch´s open
syscall.


> This really degrades NetBSD DomU performance, for example unpacking a
> sample src.tar.gz set takes 25min, while doing this in a Linux DomU only
> takes 1m and 48s (usign exactly the same Dom0).

Exactly.

Regards,

Stephan